| /* |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * distributed with this work for additional information |
| * regarding copyright ownership. The ASF licenses this file |
| * to you under the Apache License, Version 2.0 (the |
| * "License"); you may not use this file except in compliance |
| * with the License. You may obtain a copy of the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, |
| * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| * See the License for the specific language governing permissions and |
| * limitations under the License. |
| */ |
| |
| /*------------------------------------------------------------------------- |
| * |
| * selfuncs.c |
| * Selectivity functions and index cost estimation functions for |
| * standard operators and index access methods. |
| * |
| * Selectivity routines are registered in the pg_operator catalog |
| * in the "oprrest" and "oprjoin" attributes. |
| * |
| * Index cost functions are registered in the pg_am catalog |
| * in the "amcostestimate" attribute. |
| * |
| * Portions Copyright (c) 2006-2009, Greenplum inc |
| * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group |
| * Portions Copyright (c) 1994, Regents of the University of California |
| * |
| * |
| * IDENTIFICATION |
| * $PostgreSQL: pgsql/src/backend/utils/adt/selfuncs.c,v 1.214.2.6 2007/08/31 23:35:29 tgl Exp $ |
| * |
| *------------------------------------------------------------------------- |
| */ |
| |
| /*---------- |
| * Operator selectivity estimation functions are called to estimate the |
| * selectivity of WHERE clauses whose top-level operator is their operator. |
| * We divide the problem into two cases: |
| * Restriction clause estimation: the clause involves vars of just |
| * one relation. |
| * Join clause estimation: the clause involves vars of multiple rels. |
| * Join selectivity estimation is far more difficult and usually less accurate |
| * than restriction estimation. |
| * |
| * When dealing with the inner scan of a nestloop join, we consider the |
| * join's joinclauses as restriction clauses for the inner relation, and |
| * treat vars of the outer relation as parameters (a/k/a constants of unknown |
| * values). So, restriction estimators need to be able to accept an argument |
| * telling which relation is to be treated as the variable. |
| * |
| * The call convention for a restriction estimator (oprrest function) is |
| * |
| * Selectivity oprrest (PlannerInfo *root, |
| * Oid operator, |
| * List *args, |
| * int varRelid); |
| * |
| * root: general information about the query (rtable and RelOptInfo lists |
| * are particularly important for the estimator). |
| * operator: OID of the specific operator in question. |
| * args: argument list from the operator clause. |
| * varRelid: if not zero, the relid (rtable index) of the relation to |
| * be treated as the variable relation. May be zero if the args list |
| * is known to contain vars of only one relation. |
| * |
| * This is represented at the SQL level (in pg_proc) as |
| * |
| * float8 oprrest (internal, oid, internal, int4); |
| * |
| * The call convention for a join estimator (oprjoin function) is similar |
| * except that varRelid is not needed, and instead the join type is |
| * supplied: |
| * |
| * Selectivity oprjoin (PlannerInfo *root, |
| * Oid operator, |
| * List *args, |
| * JoinType jointype); |
| * |
| * float8 oprjoin (internal, oid, internal, int2); |
| * |
| * (We deliberately make the SQL signature different to facilitate |
| * catching errors.) |
| *---------- |
| */ |
| |
| #include "postgres.h" |
| |
| #include <ctype.h> |
| #include <math.h> |
| |
| #include "catalog/catquery.h" |
| #include "catalog/pg_opclass.h" |
| #include "catalog/pg_statistic.h" |
| #include "catalog/pg_type.h" |
| #include "catalog/pg_constraint.h" |
| #include "mb/pg_wchar.h" |
| #include "nodes/makefuncs.h" |
| #include "optimizer/clauses.h" |
| #include "optimizer/cost.h" |
| #include "optimizer/pathnode.h" |
| #include "optimizer/paths.h" |
| #include "optimizer/plancat.h" |
| #include "optimizer/restrictinfo.h" |
| #include "optimizer/var.h" |
| #include "parser/parse_coerce.h" |
| #include "parser/parse_expr.h" |
| #include "parser/parsetree.h" |
| #include "utils/builtins.h" |
| #include "utils/date.h" |
| #include "utils/datum.h" |
| #include "utils/fmgroids.h" |
| #include "utils/lsyscache.h" |
| #include "utils/nabstime.h" |
| #include "utils/pg_locale.h" |
| #include "utils/selfuncs.h" |
| #include "utils/syscache.h" |
| |
| #include "cdb/cdbvars.h" /* getgpsegmentCount */ |
| |
| static double ineq_histogram_selectivity(VariableStatData *vardata, |
| FmgrInfo *opproc, bool isgt, |
| Datum constval, Oid consttype); |
| static bool convert_to_scalar(Datum value, Oid valuetypid, double *scaledvalue, |
| Datum lobound, Datum hibound, Oid boundstypid, |
| double *scaledlobound, double *scaledhibound, bool isgt); |
| static double convert_numeric_to_scalar(Datum value, Oid typid); |
| static void convert_bytea_to_scalar(Datum value, |
| double *scaledvalue, |
| Datum lobound, |
| double *scaledlobound, |
| Datum hibound, |
| double *scaledhibound); |
| static double convert_one_bytea_to_scalar(unsigned char *value, int valuelen, |
| int rangelo, int rangehi); |
| static bool get_variable_maximum(PlannerInfo *root, VariableStatData *vardata, |
| Oid sortop, Datum *max); |
| static Selectivity prefix_selectivity(VariableStatData *vardata, |
| Oid opclass, Const *prefixcon); |
| static Selectivity pattern_selectivity(Const *patt, Pattern_Type ptype); |
| static Datum string_to_datum(const char *str, Oid datatype); |
| static Const *string_to_const(const char *str, Oid datatype); |
| static Const *string_to_bytea_const(const char *str, size_t str_len); |
| |
| static Selectivity |
| mcv_selectivity_cdb(VariableStatData *vardata, |
| FmgrInfo *opproc, |
| Datum constval, |
| bool varonleft, |
| Selectivity *sumcommonp, /* OUT */ |
| double *nvaluesp); /* OUT */ |
| |
| |
| |
| /* |
| * eqsel - Selectivity of "=" for any data types. |
| * |
| * Note: this routine is also used to estimate selectivity for some |
| * operators that are not "=" but have comparable selectivity behavior, |
| * such as "~=" (geometric approximate-match). Even for "=", we must |
| * keep in mind that the left and right datatypes may differ. |
| */ |
| Datum |
| eqsel(PG_FUNCTION_ARGS) |
| { |
| PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); |
| Oid operator = PG_GETARG_OID(1); |
| List *args = (List *) PG_GETARG_POINTER(2); |
| int varRelid = PG_GETARG_INT32(3); |
| VariableStatData vardata; |
| Node *other = NULL; |
| bool varonleft = false; |
| Datum *values; |
| int nvalues; |
| float4 *numbers; |
| int nnumbers; |
| double selec; |
| |
| /* |
| * If expression is not variable = something or something = variable, then |
| * punt and return a default estimate. |
| */ |
| if (!get_restriction_variable(root, args, varRelid, |
| &vardata, &other, &varonleft)) |
| PG_RETURN_FLOAT8(DEFAULT_EQ_SEL); |
| |
| /* |
| * If the something is a NULL constant, assume operator is strict and |
| * return zero, ie, operator will never return TRUE. |
| */ |
| if (IsA(other, Const) && |
| ((Const *) other)->constisnull) |
| { |
| ReleaseVariableStats(vardata); |
| PG_RETURN_FLOAT8(0.0); |
| } |
| |
| if (HeapTupleIsValid(getStatsTuple(&vardata))) |
| { |
| Form_pg_statistic stats; |
| HeapTuple tp = getStatsTuple(&vardata); |
| |
| stats = (Form_pg_statistic) GETSTRUCT(tp); |
| |
| if (IsA(other, Const)) |
| { |
| /* Variable is being compared to a known non-null constant */ |
| Datum constval = ((Const *) other)->constvalue; |
| bool match = false; |
| int i; |
| |
| /* |
| * Is the constant "=" to any of the column's most common values? |
| * (Although the given operator may not really be "=", we will |
| * assume that seeing whether it returns TRUE is an appropriate |
| * test. If you don't like this, maybe you shouldn't be using |
| * eqsel for your operator...) |
| */ |
| if (get_attstatsslot(tp, |
| vardata.atttype, vardata.atttypmod, |
| STATISTIC_KIND_MCV, InvalidOid, |
| &values, &nvalues, |
| &numbers, &nnumbers)) |
| { |
| FmgrInfo eqproc; |
| |
| fmgr_info(get_opcode(operator), &eqproc); |
| |
| for (i = 0; i < nvalues; i++) |
| { |
| /* be careful to apply operator right way 'round */ |
| if (varonleft) |
| match = DatumGetBool(FunctionCall2(&eqproc, |
| values[i], |
| constval)); |
| else |
| match = DatumGetBool(FunctionCall2(&eqproc, |
| constval, |
| values[i])); |
| if (match) |
| break; |
| } |
| } |
| else |
| { |
| /* no most-common-value info available */ |
| values = NULL; |
| numbers = NULL; |
| i = nvalues = nnumbers = 0; |
| } |
| |
| if (match) |
| { |
| /* |
| * Constant is "=" to this common value. We know selectivity |
| * exactly (or as exactly as ANALYZE could calculate it, |
| * anyway). |
| */ |
| selec = numbers[i]; |
| } |
| else |
| { |
| /* |
| * Comparison is against a constant that is neither NULL nor |
| * any of the common values. Its selectivity cannot be more |
| * than this: |
| */ |
| double sumcommon = 0.0; |
| double otherdistinct; |
| |
| for (i = 0; i < nnumbers; i++) |
| sumcommon += numbers[i]; |
| selec = 1.0 - sumcommon - stats->stanullfrac; |
| CLAMP_PROBABILITY(selec); |
| |
| /* |
| * and in fact it's probably a good deal less. We approximate |
| * that all the not-common values share this remaining |
| * fraction equally, so we divide by the number of other |
| * distinct values. |
| */ |
| otherdistinct = get_variable_numdistinct(&vardata) |
| - nnumbers; |
| if (otherdistinct > 1) |
| selec /= otherdistinct; |
| |
| /* |
| * Another cross-check: selectivity shouldn't be estimated as |
| * more than the least common "most common value". |
| */ |
| if (nnumbers > 0 && selec > numbers[nnumbers - 1]) |
| selec = numbers[nnumbers - 1]; |
| } |
| |
| free_attstatsslot(vardata.atttype, values, nvalues, |
| numbers, nnumbers); |
| } |
| else |
| { |
| double ndistinct; |
| |
| /* |
| * Search is for a value that we do not know a priori, but we will |
| * assume it is not NULL. Estimate the selectivity as non-null |
| * fraction divided by number of distinct values, so that we get a |
| * result averaged over all possible values whether common or |
| * uncommon. (Essentially, we are assuming that the not-yet-known |
| * comparison value is equally likely to be any of the possible |
| * values, regardless of their frequency in the table. Is that a |
| * good idea?) |
| */ |
| selec = 1.0 - stats->stanullfrac; |
| ndistinct = get_variable_numdistinct(&vardata); |
| if (ndistinct > 1) |
| selec /= ndistinct; |
| |
| /* |
| * Cross-check: selectivity should never be estimated as more than |
| * the most common value's. |
| */ |
| if (get_attstatsslot(tp, |
| vardata.atttype, vardata.atttypmod, |
| STATISTIC_KIND_MCV, InvalidOid, |
| NULL, NULL, |
| &numbers, &nnumbers)) |
| { |
| if (nnumbers > 0 && selec > numbers[0]) |
| selec = numbers[0]; |
| free_attstatsslot(vardata.atttype, NULL, 0, numbers, nnumbers); |
| } |
| } |
| } |
| else |
| { |
| /* |
| * No ANALYZE stats available, so make a guess using estimated number |
| * of distinct values and assuming they are equally common. (The guess |
| * is unlikely to be very good, but we do know a few special cases.) |
| */ |
| selec = 1.0 / get_variable_numdistinct(&vardata); |
| } |
| |
| ReleaseVariableStats(vardata); |
| |
| /* result should be in range, but make sure... */ |
| CLAMP_PROBABILITY(selec); |
| |
| PG_RETURN_FLOAT8((float8) selec); |
| } |
| |
| /* |
| * neqsel - Selectivity of "!=" for any data types. |
| * |
| * This routine is also used for some operators that are not "!=" |
| * but have comparable selectivity behavior. See above comments |
| * for eqsel(). |
| */ |
| Datum |
| neqsel(PG_FUNCTION_ARGS) |
| { |
| PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); |
| Oid operator = PG_GETARG_OID(1); |
| List *args = (List *) PG_GETARG_POINTER(2); |
| int varRelid = PG_GETARG_INT32(3); |
| Oid eqop; |
| float8 result; |
| |
| /* |
| * We want 1 - eqsel() where the equality operator is the one associated |
| * with this != operator, that is, its negator. |
| */ |
| eqop = get_negator(operator); |
| if (eqop) |
| { |
| result = DatumGetFloat8(DirectFunctionCall4(eqsel, |
| PointerGetDatum(root), |
| ObjectIdGetDatum(eqop), |
| PointerGetDatum(args), |
| Int32GetDatum(varRelid))); |
| } |
| else |
| { |
| /* Use default selectivity (should we raise an error instead?) */ |
| result = DEFAULT_EQ_SEL; |
| } |
| result = 1.0 - result; |
| PG_RETURN_FLOAT8(result); |
| } |
| |
| /* |
| * scalarineqsel - Selectivity of "<", "<=", ">", ">=" for scalars. |
| * |
| * This is the guts of both scalarltsel and scalargtsel. The caller has |
| * commuted the clause, if necessary, so that we can treat the variable as |
| * being on the left. The caller must also make sure that the other side |
| * of the clause is a non-null Const, and dissect same into a value and |
| * datatype. |
| * |
| * This routine works for any datatype (or pair of datatypes) known to |
| * convert_to_scalar(). If it is applied to some other datatype, |
| * it will return a default estimate. |
| */ |
| static double |
| scalarineqsel(PlannerInfo *root, Oid operator, bool isgt, |
| VariableStatData *vardata, Datum constval, Oid consttype) |
| { |
| Form_pg_statistic stats; |
| FmgrInfo opproc; |
| double mcv_selec, |
| hist_selec, |
| sumcommon; |
| double selec; |
| HeapTuple tp = getStatsTuple(vardata); |
| |
| if (!HeapTupleIsValid(getStatsTuple(vardata))) |
| { |
| /* no stats available, so default result */ |
| return DEFAULT_INEQ_SEL; |
| } |
| stats = (Form_pg_statistic) GETSTRUCT(tp); |
| |
| fmgr_info(get_opcode(operator), &opproc); |
| |
| /* |
| * If we have most-common-values info, add up the fractions of the MCV |
| * entries that satisfy MCV OP CONST. These fractions contribute directly |
| * to the result selectivity. Also add up the total fraction represented |
| * by MCV entries. |
| */ |
| mcv_selec = mcv_selectivity(vardata, &opproc, constval, true, |
| &sumcommon); |
| |
| /* |
| * If there is a histogram, determine which bin the constant falls in, and |
| * compute the resulting contribution to selectivity. |
| */ |
| hist_selec = ineq_histogram_selectivity(vardata, &opproc, isgt, |
| constval, consttype); |
| |
| /* |
| * Now merge the results from the MCV and histogram calculations, |
| * realizing that the histogram covers only the non-null values that are |
| * not listed in MCV. |
| */ |
| selec = 1.0 - stats->stanullfrac - sumcommon; |
| |
| if (hist_selec > 0.0) |
| selec *= hist_selec; |
| else |
| { |
| /* |
| * If no histogram but there are values not accounted for by MCV, |
| * arbitrarily assume half of them will match. |
| */ |
| selec *= 0.5; |
| } |
| |
| selec += mcv_selec; |
| |
| /* result should be in range, but make sure... */ |
| CLAMP_PROBABILITY(selec); |
| |
| return selec; |
| } |
| |
| /* |
| * mcv_selectivity - Examine the MCV list for selectivity estimates |
| * |
| * Determine the fraction of the variable's MCV population that satisfies |
| * the predicate (VAR OP CONST), or (CONST OP VAR) if !varonleft. Also |
| * compute the fraction of the total column population represented by the MCV |
| * list. This code will work for any boolean-returning predicate operator. |
| * |
| * The function result is the MCV selectivity, and the fraction of the |
| * total population is returned into *sumcommonp. Zeroes are returned |
| * if there is no MCV list. |
| * |
| * CDB: The number of MCVs is returned into *nvaluesp. |
| */ |
| double |
| mcv_selectivity(VariableStatData *vardata, FmgrInfo *opproc, |
| Datum constval, bool varonleft, |
| double *sumcommonp) |
| { |
| return mcv_selectivity_cdb(vardata, opproc, constval, varonleft, |
| sumcommonp, NULL); |
| } |
| |
| static Selectivity |
| mcv_selectivity_cdb(VariableStatData *vardata, |
| FmgrInfo *opproc, |
| Datum constval, |
| bool varonleft, |
| Selectivity *sumcommonp, /* OUT */ |
| double *nvaluesp) /* OUT */ |
| { |
| double mcv_selec, |
| sumcommon; |
| Datum *values; |
| int nvalues = 0; |
| float4 *numbers; |
| int nnumbers; |
| int i; |
| HeapTuple tp = getStatsTuple(vardata); |
| |
| mcv_selec = 0.0; |
| sumcommon = 0.0; |
| |
| if (HeapTupleIsValid(tp) && |
| get_attstatsslot(tp, |
| vardata->atttype, vardata->atttypmod, |
| STATISTIC_KIND_MCV, InvalidOid, |
| &values, &nvalues, |
| &numbers, &nnumbers)) |
| { |
| for (i = 0; i < nvalues; i++) |
| { |
| if (varonleft ? |
| DatumGetBool(FunctionCall2(opproc, |
| values[i], |
| constval)) : |
| DatumGetBool(FunctionCall2(opproc, |
| constval, |
| values[i]))) |
| mcv_selec += numbers[i]; |
| sumcommon += numbers[i]; |
| } |
| free_attstatsslot(vardata->atttype, values, nvalues, |
| numbers, nnumbers); |
| } |
| |
| *sumcommonp = sumcommon; |
| if (nvaluesp) |
| *nvaluesp = nvalues; |
| return mcv_selec; |
| } |
| |
| /* |
| * histogram_selectivity - Examine the histogram for selectivity estimates |
| * |
| * Determine the fraction of the variable's histogram entries that satisfy |
| * the predicate (VAR OP CONST), or (CONST OP VAR) if !varonleft. |
| * |
| * This code will work for any boolean-returning predicate operator, whether |
| * or not it has anything to do with the histogram sort operator. We are |
| * essentially using the histogram just as a representative sample. However, |
| * small histograms are unlikely to be all that representative, so the caller |
| * should specify a minimum histogram size to use, and fall back on some |
| * other approach if this routine fails. |
| * |
| * The caller also specifies n_skip, which causes us to ignore the first and |
| * last n_skip histogram elements, on the grounds that they are outliers and |
| * hence not very representative. If in doubt, min_hist_size = 100 and |
| * n_skip = 1 are reasonable values. |
| * |
| * The function result is the selectivity, or -1 if there is no histogram |
| * or it's smaller than min_hist_size. |
| * |
| * Note that the result disregards both the most-common-values (if any) and |
| * null entries. The caller is expected to combine this result with |
| * statistics for those portions of the column population. It may also be |
| * prudent to clamp the result range, ie, disbelieve exact 0 or 1 outputs. |
| */ |
| double |
| histogram_selectivity(VariableStatData *vardata, FmgrInfo *opproc, |
| Datum constval, bool varonleft, |
| int min_hist_size, int n_skip) |
| { |
| double result; |
| Datum *values; |
| int nvalues; |
| HeapTuple tp = getStatsTuple(vardata); |
| |
| /* check sanity of parameters */ |
| Assert(n_skip >= 0); |
| Assert(min_hist_size > 2 * n_skip); |
| |
| if (HeapTupleIsValid(tp) && |
| get_attstatsslot(tp, |
| vardata->atttype, vardata->atttypmod, |
| STATISTIC_KIND_HISTOGRAM, InvalidOid, |
| &values, &nvalues, |
| NULL, NULL)) |
| { |
| if (nvalues >= min_hist_size) |
| { |
| int nmatch = 0; |
| int i; |
| |
| for (i = n_skip; i < nvalues - n_skip; i++) |
| { |
| if (varonleft ? |
| DatumGetBool(FunctionCall2(opproc, |
| values[i], |
| constval)) : |
| DatumGetBool(FunctionCall2(opproc, |
| constval, |
| values[i]))) |
| nmatch++; |
| } |
| result = ((double) nmatch) / ((double) (nvalues - 2 * n_skip)); |
| } |
| else |
| result = -1; |
| free_attstatsslot(vardata->atttype, values, nvalues, NULL, 0); |
| } |
| else |
| result = -1; |
| |
| return result; |
| } |
| |
| /* |
| * ineq_histogram_selectivity - Examine the histogram for scalarineqsel |
| * |
| * Determine the fraction of the variable's histogram population that |
| * satisfies the inequality condition, ie, VAR < CONST or VAR > CONST. |
| * |
| * Returns zero if there is no histogram (valid results will always be |
| * greater than zero). |
| * |
| * Note that the result disregards both the most-common-values (if any) and |
| * null entries. The caller is expected to combine this result with |
| * statistics for those portions of the column population. |
| */ |
| static double |
| ineq_histogram_selectivity(VariableStatData *vardata, |
| FmgrInfo *opproc, bool isgt, |
| Datum constval, Oid consttype) |
| { |
| double hist_selec; |
| Datum *values; |
| int nvalues; |
| HeapTuple tp = getStatsTuple(vardata); |
| |
| hist_selec = 0.0; |
| |
| /* |
| * Someday, ANALYZE might store more than one histogram per rel/att, |
| * corresponding to more than one possible sort ordering defined for the |
| * column type. However, to make that work we will need to figure out |
| * which staop to search for --- it's not necessarily the one we have at |
| * hand! (For example, we might have a '<=' operator rather than the '<' |
| * operator that will appear in staop.) For now, assume that whatever |
| * appears in pg_statistic is sorted the same way our operator sorts, or |
| * the reverse way if isgt is TRUE. |
| */ |
| if (HeapTupleIsValid(tp) && |
| get_attstatsslot(tp, |
| vardata->atttype, vardata->atttypmod, |
| STATISTIC_KIND_HISTOGRAM, InvalidOid, |
| &values, &nvalues, |
| NULL, NULL)) |
| { |
| if (nvalues > 1) |
| { |
| /* |
| * Use binary search to find proper location, ie, the first slot |
| * at which the comparison fails. (If the given operator isn't |
| * actually sort-compatible with the histogram, you'll get garbage |
| * results ... but probably not any more garbage-y than you would |
| * from the old linear search.) |
| */ |
| double histfrac; |
| int lobound = 0; /* first possible slot to search */ |
| int hibound = nvalues; /* last+1 slot to search */ |
| |
| while (lobound < hibound) |
| { |
| int probe = (lobound + hibound) / 2; |
| bool ltcmp; |
| |
| ltcmp = DatumGetBool(FunctionCall2(opproc, |
| values[probe], |
| constval)); |
| if (isgt) |
| ltcmp = !ltcmp; |
| if (ltcmp) |
| lobound = probe + 1; |
| else |
| hibound = probe; |
| } |
| |
| if (lobound <= 0) |
| { |
| /* Constant is below lower histogram boundary. */ |
| histfrac = 0.0; |
| } |
| else if (lobound >= nvalues) |
| { |
| /* Constant is above upper histogram boundary. */ |
| histfrac = 1.0; |
| } |
| else |
| { |
| int i = lobound; |
| double val, |
| high, |
| low; |
| double binfrac; |
| |
| /* |
| * We have values[i-1] < constant < values[i]. |
| * |
| * Convert the constant and the two nearest bin boundary |
| * values to a uniform comparison scale, and do a linear |
| * interpolation within this bin. |
| */ |
| if (convert_to_scalar(constval, consttype, &val, |
| values[i - 1], values[i], |
| vardata->vartype, |
| &low, &high, isgt)) |
| { |
| if (high <= low) |
| { |
| /* cope if bin boundaries appear identical */ |
| binfrac = 0.5; |
| } |
| else if (val <= low) |
| binfrac = 0.0; |
| else if (val >= high) |
| binfrac = 1.0; |
| else |
| { |
| binfrac = (val - low) / (high - low); |
| |
| /* |
| * Watch out for the possibility that we got a NaN or |
| * Infinity from the division. This can happen |
| * despite the previous checks, if for example "low" |
| * is -Infinity. |
| */ |
| if (isnan(binfrac) || |
| binfrac < 0.0 || binfrac > 1.0) |
| binfrac = 0.5; |
| } |
| } |
| else |
| { |
| /* |
| * Ideally we'd produce an error here, on the grounds that |
| * the given operator shouldn't have scalarXXsel |
| * registered as its selectivity func unless we can deal |
| * with its operand types. But currently, all manner of |
| * stuff is invoking scalarXXsel, so give a default |
| * estimate until that can be fixed. |
| */ |
| binfrac = 0.5; |
| } |
| |
| /* |
| * Now, compute the overall selectivity across the values |
| * represented by the histogram. We have i-1 full bins and |
| * binfrac partial bin below the constant. |
| */ |
| histfrac = (double) (i - 1) + binfrac; |
| histfrac /= (double) (nvalues - 1); |
| } |
| |
| /* |
| * Now histfrac = fraction of histogram entries below the |
| * constant. |
| * |
| * Account for "<" vs ">" |
| */ |
| hist_selec = isgt ? (1.0 - histfrac) : histfrac; |
| |
| /* |
| * The histogram boundaries are only approximate to begin with, |
| * and may well be out of date anyway. Therefore, don't believe |
| * extremely small or large selectivity estimates. |
| */ |
| if (hist_selec < 0.0001) |
| hist_selec = 0.0001; |
| else if (hist_selec > 0.9999) |
| hist_selec = 0.9999; |
| } |
| |
| free_attstatsslot(vardata->atttype, values, nvalues, NULL, 0); |
| } |
| |
| return hist_selec; |
| } |
| |
| /* |
| * scalarltsel - Selectivity of "<" (also "<=") for scalars. |
| */ |
| Datum |
| scalarltsel(PG_FUNCTION_ARGS) |
| { |
| PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); |
| Oid operator = PG_GETARG_OID(1); |
| List *args = (List *) PG_GETARG_POINTER(2); |
| int varRelid = PG_GETARG_INT32(3); |
| VariableStatData vardata; |
| Node *other = NULL; |
| bool varonleft = false; |
| Datum constval; |
| Oid consttype; |
| bool isgt; |
| double selec; |
| |
| /* |
| * If expression is not variable op something or something op variable, |
| * then punt and return a default estimate. |
| */ |
| if (!get_restriction_variable(root, args, varRelid, |
| &vardata, &other, &varonleft)) |
| PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL); |
| |
| /* |
| * Can't do anything useful if the something is not a constant, either. |
| */ |
| if (!IsA(other, Const)) |
| { |
| ReleaseVariableStats(vardata); |
| PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL); |
| } |
| |
| /* |
| * If the constant is NULL, assume operator is strict and return zero, ie, |
| * operator will never return TRUE. |
| */ |
| if (((Const *) other)->constisnull) |
| { |
| ReleaseVariableStats(vardata); |
| PG_RETURN_FLOAT8(0.0); |
| } |
| constval = ((Const *) other)->constvalue; |
| consttype = ((Const *) other)->consttype; |
| |
| /* |
| * Force the var to be on the left to simplify logic in scalarineqsel. |
| */ |
| if (varonleft) |
| { |
| /* we have var < other */ |
| isgt = false; |
| } |
| else |
| { |
| /* we have other < var, commute to make var > other */ |
| operator = get_commutator(operator); |
| if (!operator) |
| { |
| /* Use default selectivity (should we raise an error instead?) */ |
| ReleaseVariableStats(vardata); |
| PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL); |
| } |
| isgt = true; |
| } |
| |
| selec = scalarineqsel(root, operator, isgt, &vardata, constval, consttype); |
| |
| ReleaseVariableStats(vardata); |
| |
| PG_RETURN_FLOAT8((float8) selec); |
| } |
| |
| /* |
| * scalargtsel - Selectivity of ">" (also ">=") for integers. |
| */ |
| Datum |
| scalargtsel(PG_FUNCTION_ARGS) |
| { |
| PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); |
| Oid operator = PG_GETARG_OID(1); |
| List *args = (List *) PG_GETARG_POINTER(2); |
| int varRelid = PG_GETARG_INT32(3); |
| VariableStatData vardata; |
| Node *other = NULL; |
| bool varonleft = false; |
| Datum constval; |
| Oid consttype; |
| bool isgt; |
| double selec; |
| |
| /* |
| * If expression is not variable op something or something op variable, |
| * then punt and return a default estimate. |
| */ |
| if (!get_restriction_variable(root, args, varRelid, |
| &vardata, &other, &varonleft)) |
| PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL); |
| |
| /* |
| * Can't do anything useful if the something is not a constant, either. |
| */ |
| if (!IsA(other, Const)) |
| { |
| ReleaseVariableStats(vardata); |
| PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL); |
| } |
| |
| /* |
| * If the constant is NULL, assume operator is strict and return zero, ie, |
| * operator will never return TRUE. |
| */ |
| if (((Const *) other)->constisnull) |
| { |
| ReleaseVariableStats(vardata); |
| PG_RETURN_FLOAT8(0.0); |
| } |
| constval = ((Const *) other)->constvalue; |
| consttype = ((Const *) other)->consttype; |
| |
| /* |
| * Force the var to be on the left to simplify logic in scalarineqsel. |
| */ |
| if (varonleft) |
| { |
| /* we have var > other */ |
| isgt = true; |
| } |
| else |
| { |
| /* we have other > var, commute to make var < other */ |
| operator = get_commutator(operator); |
| if (!operator) |
| { |
| /* Use default selectivity (should we raise an error instead?) */ |
| ReleaseVariableStats(vardata); |
| PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL); |
| } |
| isgt = false; |
| } |
| |
| selec = scalarineqsel(root, operator, isgt, &vardata, constval, consttype); |
| |
| ReleaseVariableStats(vardata); |
| |
| PG_RETURN_FLOAT8((float8) selec); |
| } |
| |
| /* |
| * patternsel - Generic code for pattern-match selectivity. |
| */ |
| static double |
| patternsel(PG_FUNCTION_ARGS, Pattern_Type ptype, bool negate) |
| { |
| PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); |
| Oid operator = PG_GETARG_OID(1); |
| List *args = (List *) PG_GETARG_POINTER(2); |
| int varRelid = PG_GETARG_INT32(3); |
| VariableStatData vardata; |
| Node *variable; |
| Node *other=NULL; |
| bool varonleft=false; |
| Datum constval; |
| Oid consttype; |
| Oid vartype; |
| Oid opclass; |
| Pattern_Prefix_Status pstatus; |
| Const *patt = NULL; |
| Const *prefix = NULL; |
| Const *rest = NULL; |
| double result; |
| |
| /* |
| * If this is for a NOT LIKE or similar operator, get the corresponding |
| * positive-match operator and work with that. Set result to the |
| * correct default estimate, too. |
| */ |
| if (negate) |
| { |
| operator = get_negator(operator); |
| if (!OidIsValid(operator)) |
| elog(ERROR, "patternsel called for operator without a negator"); |
| result = 1.0 - DEFAULT_MATCH_SEL; |
| } |
| else |
| { |
| result = DEFAULT_MATCH_SEL; |
| } |
| |
| /* |
| * If expression is not variable op constant, then punt and return a |
| * default estimate. |
| */ |
| if (!get_restriction_variable(root, args, varRelid, |
| &vardata, &other, &varonleft)) |
| return result; |
| if (!varonleft || !IsA(other, Const)) |
| { |
| ReleaseVariableStats(vardata); |
| return result; |
| } |
| variable = (Node *) linitial(args); |
| |
| /* |
| * If the constant is NULL, assume operator is strict and return zero, ie, |
| * operator will never return TRUE. (It's zero even for a negator op.) |
| */ |
| if (((Const *) other)->constisnull) |
| { |
| ReleaseVariableStats(vardata); |
| return 0.0; |
| } |
| constval = ((Const *) other)->constvalue; |
| consttype = ((Const *) other)->consttype; |
| |
| /* |
| * The right-hand const is type text or bytea for all supported operators. |
| * We do not expect to see binary-compatible types here, since |
| * const-folding should have relabeled the const to exactly match the |
| * operator's declared type. |
| */ |
| if (consttype != TEXTOID && consttype != BYTEAOID) |
| { |
| ReleaseVariableStats(vardata); |
| return result; |
| } |
| |
| /* |
| * Similarly, the exposed type of the left-hand side should be one of |
| * those we know. (Do not look at vardata.atttype, which might be |
| * something binary-compatible but different.) We can use it to choose |
| * the index opclass from which we must draw the comparison operators. |
| * |
| * NOTE: It would be more correct to use the PATTERN opclasses than the |
| * simple ones, but at the moment ANALYZE will not generate statistics for |
| * the PATTERN operators. But our results are so approximate anyway that |
| * it probably hardly matters. |
| */ |
| vartype = vardata.vartype; |
| |
| switch (vartype) |
| { |
| case TEXTOID: |
| opclass = TEXT_BTREE_OPS_OID; |
| break; |
| case VARCHAROID: |
| opclass = VARCHAR_BTREE_OPS_OID; |
| break; |
| case BPCHAROID: |
| opclass = BPCHAR_BTREE_OPS_OID; |
| break; |
| case NAMEOID: |
| opclass = NAME_BTREE_OPS_OID; |
| break; |
| case BYTEAOID: |
| opclass = BYTEA_BTREE_OPS_OID; |
| break; |
| default: |
| ReleaseVariableStats(vardata); |
| return result; |
| } |
| |
| /* divide pattern into fixed prefix and remainder */ |
| patt = (Const *) other; |
| pstatus = pattern_fixed_prefix(patt, ptype, &prefix, &rest); |
| |
| /* |
| * If necessary, coerce the prefix constant to the right type. (The "rest" |
| * constant need not be changed.) |
| */ |
| if (prefix && prefix->consttype != vartype) |
| { |
| char *prefixstr; |
| |
| switch (prefix->consttype) |
| { |
| case TEXTOID: |
| prefixstr = DatumGetCString(DirectFunctionCall1(textout, |
| prefix->constvalue)); |
| break; |
| case BYTEAOID: |
| prefixstr = DatumGetCString(DirectFunctionCall1(byteaout, |
| prefix->constvalue)); |
| break; |
| default: |
| elog(ERROR, "unrecognized consttype: %u", |
| prefix->consttype); |
| ReleaseVariableStats(vardata); |
| return result; |
| } |
| prefix = string_to_const(prefixstr, vartype); |
| pfree(prefixstr); |
| } |
| |
| if (pstatus == Pattern_Prefix_Exact) |
| { |
| /* |
| * Pattern specifies an exact match, so pretend operator is '=' |
| */ |
| Oid eqopr = get_opclass_member(opclass, InvalidOid, |
| BTEqualStrategyNumber); |
| List *eqargs; |
| |
| if (eqopr == InvalidOid) |
| elog(ERROR, "no = operator for opclass %u", opclass); |
| eqargs = list_make2(variable, prefix); |
| result = DatumGetFloat8(DirectFunctionCall4(eqsel, |
| PointerGetDatum(root), |
| ObjectIdGetDatum(eqopr), |
| PointerGetDatum(eqargs), |
| Int32GetDatum(varRelid))); |
| } |
| else |
| { |
| /* |
| * Not exact-match pattern. If we have a sufficiently large |
| * histogram, estimate selectivity for the histogram part of the |
| * population by counting matches in the histogram. If not, estimate |
| * selectivity of the fixed prefix and remainder of pattern |
| * separately, then combine the two to get an estimate of the |
| * selectivity for the part of the column population represented by |
| * the histogram. We then add up data for any most-common-values |
| * values; these are not in the histogram population, and we can get |
| * exact answers for them by applying the pattern operator, so there's |
| * no reason to approximate. (If the MCVs cover a significant part of |
| * the total population, this gives us a big leg up in accuracy.) |
| */ |
| Selectivity selec; |
| Selectivity eqsel; |
| Selectivity fewsel; |
| double fewvalues = 2.0; |
| double ncommon; |
| double ndistinct; |
| FmgrInfo opproc; |
| double nullfrac, |
| mcv_selec, |
| sumcommon; |
| |
| /* Try to use the histogram entries to get selectivity */ |
| fmgr_info(get_opcode(operator), &opproc); |
| |
| /* |
| * If we have most-common-values info, add up the fractions of the MCV |
| * entries that satisfy MCV OP PATTERN. These fractions contribute |
| * directly to the result selectivity. Also add up the total fraction |
| * represented by MCV entries. |
| */ |
| mcv_selec = mcv_selectivity_cdb(&vardata, &opproc, constval, true, |
| &sumcommon, &ncommon); |
| |
| /* CDB: LIKE cannot select fewer rows than "=". */ |
| ndistinct = get_variable_numdistinct(&vardata) - ncommon; |
| eqsel = 1.0 / Max(1.0, ndistinct); |
| |
| selec = histogram_selectivity(&vardata, &opproc, constval, true, |
| 100, 1); |
| if (selec < 0) |
| { |
| /* Nope, so fake it with the heuristic method */ |
| selec = pattern_selectivity(rest, ptype); |
| |
| if (pstatus == Pattern_Prefix_Partial) |
| { |
| Selectivity prefixsel; |
| |
| prefixsel = prefix_selectivity(&vardata, opclass, prefix); |
| |
| /* CDB: Assume prefix matches at least a few distinct values. */ |
| fewsel = (DEFAULT_RANGE_INEQ_SEL / DEFAULT_EQ_SEL) * eqsel; |
| prefixsel = Min(Max(prefixsel, fewsel), 1.0); |
| |
| selec *= prefixsel; |
| } |
| else |
| fewvalues = DEFAULT_MATCH_SEL / DEFAULT_EQ_SEL; |
| } |
| |
| /* CDB: Assume whole pattern matches at least a few distinct values. */ |
| fewsel = fewvalues * eqsel; |
| selec = Min(Max(selec, fewsel), 1.0); |
| |
| if (HeapTupleIsValid(getStatsTuple(&vardata))) |
| { |
| HeapTuple tp = getStatsTuple(&vardata); |
| nullfrac = ((Form_pg_statistic) GETSTRUCT(tp))->stanullfrac; |
| } |
| else |
| nullfrac = 0.0; |
| |
| /* |
| * Now merge the results from the MCV and histogram calculations, |
| * realizing that the histogram covers only the non-null values that |
| * are not listed in MCV. |
| */ |
| selec *= 1.0 - nullfrac - sumcommon; |
| selec += mcv_selec; |
| |
| /* result should be in range, but make sure... */ |
| CLAMP_PROBABILITY(selec); |
| result = selec; |
| } |
| |
| if (prefix) |
| { |
| pfree(DatumGetPointer(prefix->constvalue)); |
| pfree(prefix); |
| } |
| |
| ReleaseVariableStats(vardata); |
| |
| return negate ? (1.0 - result) : result; |
| } |
| |
| /* |
| * regexeqsel - Selectivity of regular-expression pattern match. |
| */ |
| Datum |
| regexeqsel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Regex, false)); |
| } |
| |
| /* |
| * icregexeqsel - Selectivity of case-insensitive regex match. |
| */ |
| Datum |
| icregexeqsel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Regex_IC, false)); |
| } |
| |
| /* |
| * likesel - Selectivity of LIKE pattern match. |
| */ |
| Datum |
| likesel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Like, false)); |
| } |
| |
| /* |
| * iclikesel - Selectivity of ILIKE pattern match. |
| */ |
| Datum |
| iclikesel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Like_IC, false)); |
| } |
| |
| /* |
| * regexnesel - Selectivity of regular-expression pattern non-match. |
| */ |
| Datum |
| regexnesel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Regex, true)); |
| } |
| |
| /* |
| * icregexnesel - Selectivity of case-insensitive regex non-match. |
| */ |
| Datum |
| icregexnesel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Regex_IC, true)); |
| } |
| |
| /* |
| * nlikesel - Selectivity of LIKE pattern non-match. |
| */ |
| Datum |
| nlikesel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Like, true)); |
| } |
| |
| /* |
| * icnlikesel - Selectivity of ILIKE pattern non-match. |
| */ |
| Datum |
| icnlikesel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternsel(fcinfo, Pattern_Type_Like_IC, true)); |
| } |
| |
| /* |
| * booltestsel - Selectivity of BooleanTest Node. |
| */ |
| Selectivity |
| booltestsel(PlannerInfo *root, BoolTestType booltesttype, Node *arg, |
| int varRelid, JoinType jointype) |
| { |
| VariableStatData vardata; |
| double selec; |
| |
| examine_variable(root, arg, varRelid, &vardata); |
| |
| if (HeapTupleIsValid(getStatsTuple(&vardata))) |
| { |
| Form_pg_statistic stats; |
| double freq_null; |
| Datum *values; |
| int nvalues; |
| float4 *numbers; |
| int nnumbers; |
| HeapTuple tp = getStatsTuple(&vardata); |
| |
| |
| stats = (Form_pg_statistic) GETSTRUCT(tp); |
| freq_null = stats->stanullfrac; |
| |
| if (get_attstatsslot(tp, |
| vardata.atttype, vardata.atttypmod, |
| STATISTIC_KIND_MCV, InvalidOid, |
| &values, &nvalues, |
| &numbers, &nnumbers) |
| && nnumbers > 0) |
| { |
| double freq_true; |
| double freq_false; |
| |
| /* |
| * Get first MCV frequency and derive frequency for true. |
| */ |
| if (DatumGetBool(values[0])) |
| freq_true = numbers[0]; |
| else |
| freq_true = 1.0 - numbers[0] - freq_null; |
| |
| /* |
| * Next derive frequency for false. Then use these as appropriate |
| * to derive frequency for each case. |
| */ |
| freq_false = 1.0 - freq_true - freq_null; |
| |
| switch (booltesttype) |
| { |
| case IS_UNKNOWN: |
| /* select only NULL values */ |
| selec = freq_null; |
| break; |
| case IS_NOT_UNKNOWN: |
| /* select non-NULL values */ |
| selec = 1.0 - freq_null; |
| break; |
| case IS_TRUE: |
| /* select only TRUE values */ |
| selec = freq_true; |
| break; |
| case IS_NOT_TRUE: |
| /* select non-TRUE values */ |
| selec = 1.0 - freq_true; |
| break; |
| case IS_FALSE: |
| /* select only FALSE values */ |
| selec = freq_false; |
| break; |
| case IS_NOT_FALSE: |
| /* select non-FALSE values */ |
| selec = 1.0 - freq_false; |
| break; |
| default: |
| elog(ERROR, "unrecognized booltesttype: %d", |
| (int) booltesttype); |
| selec = 0.0; /* Keep compiler quiet */ |
| break; |
| } |
| |
| free_attstatsslot(vardata.atttype, values, nvalues, |
| numbers, nnumbers); |
| } |
| else |
| { |
| /* |
| * No most-common-value info available. Still have null fraction |
| * information, so use it for IS [NOT] UNKNOWN. Otherwise adjust |
| * for null fraction and assume an even split for boolean tests. |
| */ |
| switch (booltesttype) |
| { |
| case IS_UNKNOWN: |
| |
| /* |
| * Use freq_null directly. |
| */ |
| selec = freq_null; |
| break; |
| case IS_NOT_UNKNOWN: |
| |
| /* |
| * Select not unknown (not null) values. Calculate from |
| * freq_null. |
| */ |
| selec = 1.0 - freq_null; |
| break; |
| case IS_TRUE: |
| case IS_NOT_TRUE: |
| case IS_FALSE: |
| case IS_NOT_FALSE: |
| selec = (1.0 - freq_null) / 2.0; |
| break; |
| default: |
| elog(ERROR, "unrecognized booltesttype: %d", |
| (int) booltesttype); |
| selec = 0.0; /* Keep compiler quiet */ |
| break; |
| } |
| } |
| } |
| else |
| { |
| /* |
| * If we can't get variable statistics for the argument, perhaps |
| * clause_selectivity can do something with it. We ignore the |
| * possibility of a NULL value when using clause_selectivity, and just |
| * assume the value is either TRUE or FALSE. |
| */ |
| switch (booltesttype) |
| { |
| case IS_UNKNOWN: |
| selec = DEFAULT_UNK_SEL; |
| break; |
| case IS_NOT_UNKNOWN: |
| selec = DEFAULT_NOT_UNK_SEL; |
| break; |
| case IS_TRUE: |
| case IS_NOT_FALSE: |
| selec = (double) clause_selectivity(root, arg, |
| varRelid, jointype, |
| false /* use_damping */); |
| break; |
| case IS_FALSE: |
| case IS_NOT_TRUE: |
| selec = 1.0 - (double) clause_selectivity(root, arg, |
| varRelid, jointype, |
| false /* use_damping */); |
| break; |
| default: |
| elog(ERROR, "unrecognized booltesttype: %d", |
| (int) booltesttype); |
| selec = 0.0; /* Keep compiler quiet */ |
| break; |
| } |
| } |
| |
| ReleaseVariableStats(vardata); |
| |
| /* result should be in range, but make sure... */ |
| CLAMP_PROBABILITY(selec); |
| |
| return (Selectivity) selec; |
| } |
| |
| /* |
| * nulltestsel - Selectivity of NullTest Node. |
| */ |
| Selectivity |
| nulltestsel(PlannerInfo *root, NullTestType nulltesttype, |
| Node *arg, int varRelid, JoinType jointype) |
| { |
| VariableStatData vardata; |
| double selec; |
| |
| /* |
| * Special hack: an IS NULL test being applied at an outer join should not |
| * be taken at face value, since it's very likely being used to select the |
| * outer-side rows that don't have a match, and thus its selectivity has |
| * nothing whatever to do with the statistics of the original table |
| * column. We do not have nearly enough context here to determine its |
| * true selectivity, so for the moment punt and guess at 0.5. Eventually |
| * the planner should be made to provide enough info about the clause's |
| * context to let us do better. |
| */ |
| if (IS_OUTER_JOIN(jointype) && nulltesttype == IS_NULL) |
| return (Selectivity) 0.5; |
| |
| examine_variable(root, arg, varRelid, &vardata); |
| |
| if (HeapTupleIsValid(getStatsTuple(&vardata))) |
| { |
| Form_pg_statistic stats; |
| HeapTuple tp = getStatsTuple(&vardata); |
| double freq_null; |
| |
| stats = (Form_pg_statistic) GETSTRUCT(tp); |
| freq_null = stats->stanullfrac; |
| |
| switch (nulltesttype) |
| { |
| case IS_NULL: |
| |
| /* |
| * Use freq_null directly. |
| */ |
| selec = freq_null; |
| break; |
| case IS_NOT_NULL: |
| |
| /* |
| * Select not unknown (not null) values. Calculate from |
| * freq_null. |
| */ |
| selec = 1.0 - freq_null; |
| break; |
| default: |
| elog(ERROR, "unrecognized nulltesttype: %d", |
| (int) nulltesttype); |
| return (Selectivity) 0; /* keep compiler quiet */ |
| } |
| } |
| else |
| { |
| /* |
| * No ANALYZE stats available, so make a guess |
| */ |
| switch (nulltesttype) |
| { |
| case IS_NULL: |
| selec = DEFAULT_UNK_SEL; |
| break; |
| case IS_NOT_NULL: |
| selec = DEFAULT_NOT_UNK_SEL; |
| break; |
| default: |
| elog(ERROR, "unrecognized nulltesttype: %d", |
| (int) nulltesttype); |
| return (Selectivity) 0; /* keep compiler quiet */ |
| } |
| } |
| |
| ReleaseVariableStats(vardata); |
| |
| /* result should be in range, but make sure... */ |
| CLAMP_PROBABILITY(selec); |
| |
| return (Selectivity) selec; |
| } |
| |
| /* |
| * strip_array_coercion - strip binary-compatible relabeling from an array expr |
| * |
| * For array values, the parser doesn't generate simple RelabelType nodes, |
| * but function calls of array_type_coerce() or array_type_length_coerce(). |
| * If we want to cope with binary-compatible situations we have to look |
| * through these calls whenever the element-type coercion is binary-compatible. |
| */ |
| static Node * |
| strip_array_coercion(Node *node) |
| { |
| /* could be more than one level, so loop */ |
| for (;;) |
| { |
| if (node && IsA(node, RelabelType)) |
| { |
| /* We don't really expect this case, but may as well cope */ |
| node = (Node *) ((RelabelType *) node)->arg; |
| } |
| else if (node && IsA(node, FuncExpr)) |
| { |
| FuncExpr *fexpr = (FuncExpr *) node; |
| Node *arg1; |
| Oid src_elem_type; |
| Oid tgt_elem_type; |
| Oid funcId; |
| |
| /* must be the right function(s) */ |
| if (!(fexpr->funcid == F_ARRAY_TYPE_COERCE || |
| fexpr->funcid == F_ARRAY_TYPE_LENGTH_COERCE)) |
| break; |
| |
| /* fetch source and destination array element types */ |
| arg1 = (Node *) linitial(fexpr->args); |
| src_elem_type = get_element_type(exprType(arg1)); |
| if (src_elem_type == InvalidOid) |
| break; /* probably shouldn't happen */ |
| tgt_elem_type = get_element_type(fexpr->funcresulttype); |
| if (tgt_elem_type == InvalidOid) |
| break; /* probably shouldn't happen */ |
| |
| /* find out how to coerce */ |
| if (!find_coercion_pathway(tgt_elem_type, src_elem_type, |
| COERCION_EXPLICIT, &funcId)) |
| break; /* definitely shouldn't happen */ |
| |
| if (OidIsValid(funcId)) |
| break; /* non-binary-compatible coercion */ |
| |
| node = arg1; /* OK to look through the node */ |
| } |
| else |
| break; |
| } |
| return node; |
| } |
| |
| /* |
| * scalararraysel - Selectivity of ScalarArrayOpExpr Node. |
| */ |
| Selectivity |
| scalararraysel(PlannerInfo *root, |
| ScalarArrayOpExpr *clause, |
| bool is_join_clause, |
| int varRelid, JoinType jointype) |
| { |
| Oid operator = clause->opno; |
| bool useOr = clause->useOr; |
| Node *leftop; |
| Node *rightop; |
| Oid nominal_element_type; |
| RegProcedure oprsel; |
| FmgrInfo oprselproc; |
| Datum selarg4; |
| Selectivity s1; |
| |
| /* |
| * First, look up the underlying operator's selectivity estimator. Punt if |
| * it hasn't got one. |
| */ |
| if (is_join_clause) |
| { |
| oprsel = get_oprjoin(operator); |
| selarg4 = Int16GetDatum(jointype); |
| } |
| else |
| { |
| oprsel = get_oprrest(operator); |
| selarg4 = Int32GetDatum(varRelid); |
| } |
| if (!oprsel) |
| return (Selectivity) 0.5; |
| fmgr_info(oprsel, &oprselproc); |
| |
| /* deconstruct the expression */ |
| Assert(list_length(clause->args) == 2); |
| leftop = (Node *) linitial(clause->args); |
| rightop = (Node *) lsecond(clause->args); |
| |
| /* get nominal (after relabeling) element type of rightop */ |
| nominal_element_type = get_element_type(exprType(rightop)); |
| if (!OidIsValid(nominal_element_type)) |
| return (Selectivity) 0.5; /* probably shouldn't happen */ |
| |
| /* look through any binary-compatible relabeling of rightop */ |
| rightop = strip_array_coercion(rightop); |
| |
| /* |
| * We consider three cases: |
| * |
| * 1. rightop is an Array constant: deconstruct the array, apply the |
| * operator's selectivity function for each array element, and merge the |
| * results in the same way that clausesel.c does for AND/OR combinations. |
| * |
| * 2. rightop is an ARRAY[] construct: apply the operator's selectivity |
| * function for each element of the ARRAY[] construct, and merge. |
| * |
| * 3. otherwise, make a guess ... |
| */ |
| if (rightop && IsA(rightop, Const)) |
| { |
| Datum arraydatum = ((Const *) rightop)->constvalue; |
| bool arrayisnull = ((Const *) rightop)->constisnull; |
| ArrayType *arrayval; |
| int16 elmlen; |
| bool elmbyval; |
| char elmalign; |
| int num_elems; |
| Datum *elem_values; |
| bool *elem_nulls; |
| int i; |
| |
| if (arrayisnull) /* qual can't succeed if null array */ |
| return (Selectivity) 0.0; |
| arrayval = DatumGetArrayTypeP(arraydatum); |
| get_typlenbyvalalign(ARR_ELEMTYPE(arrayval), |
| &elmlen, &elmbyval, &elmalign); |
| deconstruct_array(arrayval, |
| ARR_ELEMTYPE(arrayval), |
| elmlen, elmbyval, elmalign, |
| &elem_values, &elem_nulls, &num_elems); |
| s1 = useOr ? 0.0 : 1.0; |
| for (i = 0; i < num_elems; i++) |
| { |
| List *args; |
| Selectivity s2; |
| |
| args = list_make2(leftop, |
| makeConst(nominal_element_type, -1, |
| elmlen, |
| elem_values[i], |
| elem_nulls[i], |
| elmbyval)); |
| s2 = DatumGetFloat8(FunctionCall4(&oprselproc, |
| PointerGetDatum(root), |
| ObjectIdGetDatum(operator), |
| PointerGetDatum(args), |
| selarg4)); |
| if (useOr) |
| s1 = s1 + s2 - s1 * s2; |
| else |
| s1 = s1 * s2; |
| } |
| } |
| else if (rightop && IsA(rightop, ArrayExpr) && |
| !((ArrayExpr *) rightop)->multidims) |
| { |
| ArrayExpr *arrayexpr = (ArrayExpr *) rightop; |
| int16 elmlen; |
| bool elmbyval; |
| ListCell *l; |
| |
| get_typlenbyval(arrayexpr->element_typeid, |
| &elmlen, &elmbyval); |
| s1 = useOr ? 0.0 : 1.0; |
| foreach(l, arrayexpr->elements) |
| { |
| Node *elem = (Node *) lfirst(l); |
| List *args; |
| Selectivity s2; |
| |
| /* |
| * Theoretically, if elem isn't of nominal_element_type we should |
| * insert a RelabelType, but it seems unlikely that any operator |
| * estimation function would really care ... |
| */ |
| args = list_make2(leftop, elem); |
| s2 = DatumGetFloat8(FunctionCall4(&oprselproc, |
| PointerGetDatum(root), |
| ObjectIdGetDatum(operator), |
| PointerGetDatum(args), |
| selarg4)); |
| if (useOr) |
| s1 = s1 + s2 - s1 * s2; |
| else |
| s1 = s1 * s2; |
| } |
| } |
| else |
| { |
| CaseTestExpr *dummyexpr; |
| List *args; |
| Selectivity s2; |
| int i; |
| |
| /* |
| * We need a dummy rightop to pass to the operator selectivity |
| * routine. It can be pretty much anything that doesn't look like a |
| * constant; CaseTestExpr is a convenient choice. |
| */ |
| dummyexpr = makeNode(CaseTestExpr); |
| dummyexpr->typeId = nominal_element_type; |
| dummyexpr->typeMod = -1; |
| args = list_make2(leftop, dummyexpr); |
| s2 = DatumGetFloat8(FunctionCall4(&oprselproc, |
| PointerGetDatum(root), |
| ObjectIdGetDatum(operator), |
| PointerGetDatum(args), |
| selarg4)); |
| s1 = useOr ? 0.0 : 1.0; |
| |
| /* |
| * Arbitrarily assume 10 elements in the eventual array value (see |
| * also estimate_array_length) |
| */ |
| for (i = 0; i < 10; i++) |
| { |
| if (useOr) |
| s1 = s1 + s2 - s1 * s2; |
| else |
| s1 = s1 * s2; |
| } |
| } |
| |
| /* result should be in range, but make sure... */ |
| CLAMP_PROBABILITY(s1); |
| |
| return s1; |
| } |
| |
| /* |
| * Estimate number of elements in the array yielded by an expression. |
| * |
| * It's important that this agree with scalararraysel. |
| */ |
| int |
| estimate_array_length(Node *arrayexpr) |
| { |
| /* look through any binary-compatible relabeling of arrayexpr */ |
| arrayexpr = strip_array_coercion(arrayexpr); |
| |
| if (arrayexpr && IsA(arrayexpr, Const)) |
| { |
| Datum arraydatum = ((Const *) arrayexpr)->constvalue; |
| bool arrayisnull = ((Const *) arrayexpr)->constisnull; |
| ArrayType *arrayval; |
| |
| if (arrayisnull) |
| return 0; |
| arrayval = DatumGetArrayTypeP(arraydatum); |
| return ArrayGetNItems(ARR_NDIM(arrayval), ARR_DIMS(arrayval)); |
| } |
| else if (arrayexpr && IsA(arrayexpr, ArrayExpr) && |
| !((ArrayExpr *) arrayexpr)->multidims) |
| { |
| return list_length(((ArrayExpr *) arrayexpr)->elements); |
| } |
| else |
| { |
| /* default guess --- see also scalararraysel */ |
| return 10; |
| } |
| } |
| |
| /* |
| * rowcomparesel - Selectivity of RowCompareExpr Node. |
| * |
| * We estimate RowCompare selectivity by considering just the first (high |
| * order) columns, which makes it equivalent to an ordinary OpExpr. While |
| * this estimate could be refined by considering additional columns, it |
| * seems unlikely that we could do a lot better without multi-column |
| * statistics. |
| */ |
| Selectivity |
| rowcomparesel(PlannerInfo *root, |
| RowCompareExpr *clause, |
| int varRelid, JoinType jointype) |
| { |
| Selectivity s1; |
| Oid opno = linitial_oid(clause->opnos); |
| List *opargs; |
| bool is_join_clause; |
| |
| /* Build equivalent arg list for single operator */ |
| opargs = list_make2(linitial(clause->largs), linitial(clause->rargs)); |
| |
| /* Decide if it's a join clause, same as for OpExpr */ |
| if (varRelid != 0) |
| { |
| /* |
| * If we are considering a nestloop join then all clauses are |
| * restriction clauses, since we are only interested in the one |
| * relation. |
| */ |
| is_join_clause = false; |
| } |
| else |
| { |
| /* |
| * Otherwise, it's a join if there's more than one relation used. |
| * Notice we ignore the low-order columns here. |
| */ |
| is_join_clause = (NumRelids((Node *) opargs) > 1); |
| } |
| |
| if (is_join_clause) |
| { |
| /* Estimate selectivity for a join clause. */ |
| s1 = join_selectivity(root, opno, |
| opargs, |
| jointype); |
| } |
| else |
| { |
| /* Estimate selectivity for a restriction clause. */ |
| s1 = restriction_selectivity(root, opno, |
| opargs, |
| varRelid); |
| } |
| |
| return s1; |
| } |
| |
| /* |
| * eqjoinsel - Join selectivity of "=" |
| */ |
| Datum |
| eqjoinsel(PG_FUNCTION_ARGS) |
| { |
| PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); |
| Oid operator = PG_GETARG_OID(1); |
| List *args = (List *) PG_GETARG_POINTER(2); |
| JoinType jointype = (JoinType) PG_GETARG_INT16(3); |
| double selec; |
| VariableStatData vardata1; |
| VariableStatData vardata2; |
| double nd1; |
| double nd2; |
| Form_pg_statistic stats1 = NULL; |
| Form_pg_statistic stats2 = NULL; |
| bool have_mcvs1 = false; |
| Datum *values1 = NULL; |
| int nvalues1 = 0; |
| float4 *numbers1 = NULL; |
| int nnumbers1 = 0; |
| bool have_mcvs2 = false; |
| Datum *values2 = NULL; |
| int nvalues2 = 0; |
| float4 *numbers2 = NULL; |
| int nnumbers2 = 0; |
| |
| get_join_variables(root, args, &vardata1, &vardata2); |
| |
| nd1 = get_variable_numdistinct(&vardata1); |
| nd2 = get_variable_numdistinct(&vardata2); |
| |
| if (HeapTupleIsValid(getStatsTuple(&vardata1))) |
| { |
| HeapTuple tp = getStatsTuple(&vardata1); |
| stats1 = (Form_pg_statistic) GETSTRUCT(tp); |
| have_mcvs1 = get_attstatsslot(tp, |
| vardata1.atttype, |
| vardata1.atttypmod, |
| STATISTIC_KIND_MCV, |
| InvalidOid, |
| &values1, &nvalues1, |
| &numbers1, &nnumbers1); |
| } |
| |
| if (HeapTupleIsValid(getStatsTuple(&vardata2))) |
| { |
| HeapTuple tp = getStatsTuple(&vardata2); |
| stats2 = (Form_pg_statistic) GETSTRUCT(tp); |
| have_mcvs2 = get_attstatsslot(tp, |
| vardata2.atttype, |
| vardata2.atttypmod, |
| STATISTIC_KIND_MCV, |
| InvalidOid, |
| &values2, &nvalues2, |
| &numbers2, &nnumbers2); |
| } |
| |
| if (have_mcvs1 && have_mcvs2) |
| { |
| /* |
| * We have most-common-value lists for both relations. Run through |
| * the lists to see which MCVs actually join to each other with the |
| * given operator. This allows us to determine the exact join |
| * selectivity for the portion of the relations represented by the MCV |
| * lists. We still have to estimate for the remaining population, but |
| * in a skewed distribution this gives us a big leg up in accuracy. |
| * For motivation see the analysis in Y. Ioannidis and S. |
| * Christodoulakis, "On the propagation of errors in the size of join |
| * results", Technical Report 1018, Computer Science Dept., University |
| * of Wisconsin, Madison, March 1991 (available from ftp.cs.wisc.edu). |
| */ |
| FmgrInfo eqproc; |
| bool *hasmatch1; |
| bool *hasmatch2; |
| double nullfrac1 = stats1->stanullfrac; |
| double nullfrac2 = stats2->stanullfrac; |
| double matchprodfreq, |
| matchfreq1, |
| matchfreq2, |
| unmatchfreq1, |
| unmatchfreq2, |
| otherfreq1, |
| otherfreq2, |
| totalsel1, |
| totalsel2; |
| int i, |
| nmatches; |
| |
| fmgr_info(get_opcode(operator), &eqproc); |
| hasmatch1 = (bool *) palloc0(nvalues1 * sizeof(bool)); |
| hasmatch2 = (bool *) palloc0(nvalues2 * sizeof(bool)); |
| |
| /* |
| * If we are doing any variant of JOIN_IN, pretend all the values of |
| * the righthand relation are unique (ie, act as if it's been |
| * DISTINCT'd). |
| * |
| * NOTE: it might seem that we should unique-ify the lefthand input |
| * when considering JOIN_REVERSE_IN. But this is not so, because the |
| * join clause we've been handed has not been commuted from the way |
| * the parser originally wrote it. We know that the unique side of |
| * the IN clause is *always* on the right. |
| * |
| * NOTE: it would be dangerous to try to be smart about JOIN_LEFT or |
| * JOIN_RIGHT here, because we do not have enough information to |
| * determine which var is really on which side of the join. Perhaps |
| * someday we should pass in more information. |
| */ |
| if (jointype == JOIN_IN) |
| { |
| float4 oneovern = 1.0 / nd2; |
| |
| for (i = 0; i < nvalues2; i++) |
| numbers2[i] = oneovern; |
| nullfrac2 = oneovern; |
| } |
| |
| /* |
| * Note we assume that each MCV will match at most one member of the |
| * other MCV list. If the operator isn't really equality, there could |
| * be multiple matches --- but we don't look for them, both for speed |
| * and because the math wouldn't add up... |
| */ |
| matchprodfreq = 0.0; |
| nmatches = 0; |
| for (i = 0; i < nvalues1; i++) |
| { |
| int j; |
| |
| for (j = 0; j < nvalues2; j++) |
| { |
| if (hasmatch2[j]) |
| continue; |
| if (DatumGetBool(FunctionCall2(&eqproc, |
| values1[i], |
| values2[j]))) |
| { |
| hasmatch1[i] = hasmatch2[j] = true; |
| matchprodfreq += numbers1[i] * numbers2[j]; |
| nmatches++; |
| break; |
| } |
| } |
| } |
| CLAMP_PROBABILITY(matchprodfreq); |
| /* Sum up frequencies of matched and unmatched MCVs */ |
| matchfreq1 = unmatchfreq1 = 0.0; |
| for (i = 0; i < nvalues1; i++) |
| { |
| if (hasmatch1[i]) |
| matchfreq1 += numbers1[i]; |
| else |
| unmatchfreq1 += numbers1[i]; |
| } |
| CLAMP_PROBABILITY(matchfreq1); |
| CLAMP_PROBABILITY(unmatchfreq1); |
| matchfreq2 = unmatchfreq2 = 0.0; |
| for (i = 0; i < nvalues2; i++) |
| { |
| if (hasmatch2[i]) |
| matchfreq2 += numbers2[i]; |
| else |
| unmatchfreq2 += numbers2[i]; |
| } |
| CLAMP_PROBABILITY(matchfreq2); |
| CLAMP_PROBABILITY(unmatchfreq2); |
| pfree(hasmatch1); |
| pfree(hasmatch2); |
| |
| /* |
| * Compute total frequency of non-null values that are not in the MCV |
| * lists. |
| */ |
| otherfreq1 = 1.0 - nullfrac1 - matchfreq1 - unmatchfreq1; |
| otherfreq2 = 1.0 - nullfrac2 - matchfreq2 - unmatchfreq2; |
| CLAMP_PROBABILITY(otherfreq1); |
| CLAMP_PROBABILITY(otherfreq2); |
| |
| /* |
| * We can estimate the total selectivity from the point of view of |
| * relation 1 as: the known selectivity for matched MCVs, plus |
| * unmatched MCVs that are assumed to match against random members of |
| * relation 2's non-MCV population, plus non-MCV values that are |
| * assumed to match against random members of relation 2's unmatched |
| * MCVs plus non-MCV values. |
| */ |
| totalsel1 = matchprodfreq; |
| if (nd2 > nvalues2) |
| totalsel1 += unmatchfreq1 * otherfreq2 / (nd2 - nvalues2); |
| if (nd2 > nmatches) |
| totalsel1 += otherfreq1 * (otherfreq2 + unmatchfreq2) / |
| (nd2 - nmatches); |
| /* Same estimate from the point of view of relation 2. */ |
| totalsel2 = matchprodfreq; |
| if (nd1 > nvalues1) |
| totalsel2 += unmatchfreq2 * otherfreq1 / (nd1 - nvalues1); |
| if (nd1 > nmatches) |
| totalsel2 += otherfreq2 * (otherfreq1 + unmatchfreq1) / |
| (nd1 - nmatches); |
| |
| /* |
| * Use the smaller of the two estimates. This can be justified in |
| * essentially the same terms as given below for the no-stats case: to |
| * a first approximation, we are estimating from the point of view of |
| * the relation with smaller nd. |
| */ |
| selec = (totalsel1 < totalsel2) ? totalsel1 : totalsel2; |
| } |
| else |
| { |
| /* |
| * We do not have MCV lists for both sides. Estimate the join |
| * selectivity as MIN(1/nd1,1/nd2)*(1-nullfrac1)*(1-nullfrac2). This |
| * is plausible if we assume that the join operator is strict and the |
| * non-null values are about equally distributed: a given non-null |
| * tuple of rel1 will join to either zero or N2*(1-nullfrac2)/nd2 rows |
| * of rel2, so total join rows are at most |
| * N1*(1-nullfrac1)*N2*(1-nullfrac2)/nd2 giving a join selectivity of |
| * not more than (1-nullfrac1)*(1-nullfrac2)/nd2. By the same logic it |
| * is not more than (1-nullfrac1)*(1-nullfrac2)/nd1, so the expression |
| * with MIN() is an upper bound. Using the MIN() means we estimate |
| * from the point of view of the relation with smaller nd (since the |
| * larger nd is determining the MIN). It is reasonable to assume that |
| * most tuples in this rel will have join partners, so the bound is |
| * probably reasonably tight and should be taken as-is. |
| * |
| * XXX Can we be smarter if we have an MCV list for just one side? It |
| * seems that if we assume equal distribution for the other side, we |
| * end up with the same answer anyway. |
| */ |
| double nullfrac1 = stats1 ? stats1->stanullfrac : 0.0; |
| double nullfrac2 = stats2 ? stats2->stanullfrac : 0.0; |
| |
| selec = (1.0 - nullfrac1) * (1.0 - nullfrac2); |
| if (nd1 > nd2) |
| selec /= nd1; |
| else |
| selec /= nd2; |
| } |
| |
| if (have_mcvs1) |
| free_attstatsslot(vardata1.atttype, values1, nvalues1, |
| numbers1, nnumbers1); |
| if (have_mcvs2) |
| free_attstatsslot(vardata2.atttype, values2, nvalues2, |
| numbers2, nnumbers2); |
| |
| ReleaseVariableStats(vardata1); |
| ReleaseVariableStats(vardata2); |
| |
| CLAMP_PROBABILITY(selec); |
| |
| PG_RETURN_FLOAT8((float8) selec); |
| } |
| |
| /* |
| * neqjoinsel - Join selectivity of "!=" |
| */ |
| Datum |
| neqjoinsel(PG_FUNCTION_ARGS) |
| { |
| PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); |
| Oid operator = PG_GETARG_OID(1); |
| List *args = (List *) PG_GETARG_POINTER(2); |
| JoinType jointype = (JoinType) PG_GETARG_INT16(3); |
| Oid eqop; |
| float8 result; |
| |
| /* |
| * We want 1 - eqjoinsel() where the equality operator is the one |
| * associated with this != operator, that is, its negator. |
| */ |
| eqop = get_negator(operator); |
| if (eqop) |
| { |
| result = DatumGetFloat8(DirectFunctionCall4(eqjoinsel, |
| PointerGetDatum(root), |
| ObjectIdGetDatum(eqop), |
| PointerGetDatum(args), |
| Int16GetDatum(jointype))); |
| } |
| else |
| { |
| /* Use default selectivity (should we raise an error instead?) */ |
| result = DEFAULT_EQ_SEL; |
| } |
| result = 1.0 - result; |
| PG_RETURN_FLOAT8(result); |
| } |
| |
| /* |
| * scalarltjoinsel - Join selectivity of "<" and "<=" for scalars |
| */ |
| Datum |
| scalarltjoinsel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL); |
| } |
| |
| /* |
| * scalargtjoinsel - Join selectivity of ">" and ">=" for scalars |
| */ |
| Datum |
| scalargtjoinsel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(DEFAULT_INEQ_SEL); |
| } |
| |
| /* |
| * patternjoinsel - Generic code for pattern-match join selectivity. |
| */ |
| static double |
| patternjoinsel(PG_FUNCTION_ARGS, Pattern_Type ptype, bool negate) |
| { |
| /* For the moment we just punt. */ |
| return negate ? (1.0 - DEFAULT_MATCH_SEL) : DEFAULT_MATCH_SEL; |
| } |
| |
| /* |
| * regexeqjoinsel - Join selectivity of regular-expression pattern match. |
| */ |
| Datum |
| regexeqjoinsel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Regex, false)); |
| } |
| |
| /* |
| * icregexeqjoinsel - Join selectivity of case-insensitive regex match. |
| */ |
| Datum |
| icregexeqjoinsel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Regex_IC, false)); |
| } |
| |
| /* |
| * likejoinsel - Join selectivity of LIKE pattern match. |
| */ |
| Datum |
| likejoinsel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Like, false)); |
| } |
| |
| /* |
| * iclikejoinsel - Join selectivity of ILIKE pattern match. |
| */ |
| Datum |
| iclikejoinsel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Like_IC, false)); |
| } |
| |
| /* |
| * regexnejoinsel - Join selectivity of regex non-match. |
| */ |
| Datum |
| regexnejoinsel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Regex, true)); |
| } |
| |
| /* |
| * icregexnejoinsel - Join selectivity of case-insensitive regex non-match. |
| */ |
| Datum |
| icregexnejoinsel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Regex_IC, true)); |
| } |
| |
| /* |
| * nlikejoinsel - Join selectivity of LIKE pattern non-match. |
| */ |
| Datum |
| nlikejoinsel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Like, true)); |
| } |
| |
| /* |
| * icnlikejoinsel - Join selectivity of ILIKE pattern non-match. |
| */ |
| Datum |
| icnlikejoinsel(PG_FUNCTION_ARGS) |
| { |
| PG_RETURN_FLOAT8(patternjoinsel(fcinfo, Pattern_Type_Like_IC, true)); |
| } |
| |
| /* |
| * mergejoinscansel - Scan selectivity of merge join. |
| * |
| * A merge join will stop as soon as it exhausts either input stream. |
| * Therefore, if we can estimate the ranges of both input variables, |
| * we can estimate how much of the input will actually be read. This |
| * can have a considerable impact on the cost when using indexscans. |
| * |
| * clause should be a clause already known to be mergejoinable. |
| * |
| * *leftscan is set to the fraction of the left-hand variable expected |
| * to be scanned (0 to 1), and similarly *rightscan for the right-hand |
| * variable. |
| */ |
| void |
| mergejoinscansel(PlannerInfo *root, Node *clause, |
| Selectivity *leftscan, |
| Selectivity *rightscan) |
| { |
| Node *left, |
| *right; |
| VariableStatData leftvar, |
| rightvar; |
| Oid lefttype, |
| righttype; |
| Oid opno, |
| lsortop, |
| rsortop, |
| ltop, |
| gtop, |
| leop, |
| revgtop, |
| revleop; |
| Datum leftmax = 0, |
| rightmax = 0; |
| double selec; |
| |
| /* Set default results if we can't figure anything out. */ |
| *leftscan = *rightscan = 1.0; |
| |
| /* Deconstruct the merge clause */ |
| if (!is_opclause(clause)) |
| return; /* shouldn't happen */ |
| opno = ((OpExpr *) clause)->opno; |
| left = get_leftop((Expr *) clause); |
| right = get_rightop((Expr *) clause); |
| if (!right) |
| return; /* shouldn't happen */ |
| |
| /* Look for stats for the inputs */ |
| examine_variable(root, left, 0, &leftvar); |
| examine_variable(root, right, 0, &rightvar); |
| |
| /* Get the direct input types of the operator */ |
| lefttype = exprType(left); |
| righttype = exprType(right); |
| |
| /* Verify mergejoinability and get left and right "<" operators */ |
| if (!op_mergejoinable(opno, |
| &lsortop, |
| &rsortop)) |
| goto fail; /* shouldn't happen */ |
| |
| /* Try to get maximum values of both inputs */ |
| if (!get_variable_maximum(root, &leftvar, lsortop, &leftmax)) |
| goto fail; /* no max available from stats */ |
| |
| if (!get_variable_maximum(root, &rightvar, rsortop, &rightmax)) |
| goto fail; /* no max available from stats */ |
| |
| /* Look up the "left < right" and "left > right" operators */ |
| op_mergejoin_crossops(opno, <op, >op, NULL, NULL); |
| |
| /* Look up the "left <= right" operator */ |
| leop = get_negator(gtop); |
| if (!OidIsValid(leop)) |
| goto fail; /* insufficient info in catalogs */ |
| |
| /* Look up the "right > left" operator */ |
| revgtop = get_commutator(ltop); |
| if (!OidIsValid(revgtop)) |
| goto fail; /* insufficient info in catalogs */ |
| |
| /* Look up the "right <= left" operator */ |
| revleop = get_negator(revgtop); |
| if (!OidIsValid(revleop)) |
| goto fail; /* insufficient info in catalogs */ |
| |
| /* |
| * Now, the fraction of the left variable that will be scanned is the |
| * fraction that's <= the right-side maximum value. But only believe |
| * non-default estimates, else stick with our 1.0. |
| */ |
| selec = scalarineqsel(root, leop, false, &leftvar, |
| rightmax, righttype); |
| if (selec != DEFAULT_INEQ_SEL) |
| *leftscan = selec; |
| |
| /* And similarly for the right variable. */ |
| selec = scalarineqsel(root, revleop, false, &rightvar, |
| leftmax, lefttype); |
| if (selec != DEFAULT_INEQ_SEL) |
| *rightscan = selec; |
| |
| /* |
| * Only one of the two fractions can really be less than 1.0; believe the |
| * smaller estimate and reset the other one to exactly 1.0. If we get |
| * exactly equal estimates (as can easily happen with self-joins), believe |
| * neither. |
| */ |
| if (*leftscan > *rightscan) |
| *leftscan = 1.0; |
| else if (*leftscan < *rightscan) |
| *rightscan = 1.0; |
| else |
| *leftscan = *rightscan = 1.0; |
| |
| fail: |
| ReleaseVariableStats(leftvar); |
| ReleaseVariableStats(rightvar); |
| } |
| |
| |
| /* |
| * Helper routine for estimate_num_groups: add an item to a list of |
| * GroupVarInfos, but only if it's not known equal to any of the existing |
| * entries. |
| */ |
| typedef struct |
| { |
| Node *var; /* might be an expression, not just a Var */ |
| RelOptInfo *rel; /* relation it belongs to */ |
| double ndistinct; /* # distinct values */ |
| } GroupVarInfo; |
| |
| static List * |
| add_unique_group_var(PlannerInfo *root, List *varinfos, |
| Node *var, VariableStatData *vardata) |
| { |
| GroupVarInfo *varinfo; |
| double ndistinct; |
| ListCell *lc; |
| |
| ndistinct = get_variable_numdistinct(vardata); |
| |
| /* cannot use foreach here because of possible list_delete */ |
| lc = list_head(varinfos); |
| while (lc) |
| { |
| varinfo = (GroupVarInfo *) lfirst(lc); |
| |
| /* must advance lc before list_delete possibly pfree's it */ |
| lc = lnext(lc); |
| |
| /* Drop exact duplicates */ |
| if (equal(var, varinfo->var)) |
| return varinfos; |
| |
| /* |
| * Drop known-equal vars, but only if they belong to different |
| * relations (see comments for estimate_num_groups) |
| */ |
| if (vardata->rel != varinfo->rel && |
| exprs_known_equal(root, var, varinfo->var)) |
| { |
| if (varinfo->ndistinct <= ndistinct) |
| { |
| /* Keep older item, forget new one */ |
| return varinfos; |
| } |
| else |
| { |
| /* Delete the older item */ |
| varinfos = list_delete_ptr(varinfos, varinfo); |
| } |
| } |
| } |
| |
| varinfo = (GroupVarInfo *) palloc(sizeof(GroupVarInfo)); |
| |
| varinfo->var = var; |
| varinfo->rel = vardata->rel; |
| varinfo->ndistinct = ndistinct; |
| varinfos = lappend(varinfos, varinfo); |
| return varinfos; |
| } |
| |
| /* |
| * estimate_num_groups - Estimate number of groups in a grouped query |
| * |
| * Given a query having a GROUP BY clause, estimate how many groups there |
| * will be --- ie, the number of distinct combinations of the GROUP BY |
| * expressions. |
| * |
| * This routine is also used to estimate the number of rows emitted by |
| * a DISTINCT filtering step; that is an isomorphic problem. (Note: |
| * actually, we only use it for DISTINCT when there's no grouping or |
| * aggregation ahead of the DISTINCT.) |
| * |
| * Inputs: |
| * root - the query |
| * groupExprs - list of expressions being grouped by |
| * input_rows - number of rows estimated to arrive at the group/unique |
| * filter step |
| * |
| * Given the lack of any cross-correlation statistics in the system, it's |
| * impossible to do anything really trustworthy with GROUP BY conditions |
| * involving multiple Vars. We should however avoid assuming the worst |
| * case (all possible cross-product terms actually appear as groups) since |
| * very often the grouped-by Vars are highly correlated. Our current approach |
| * is as follows: |
| * 1. Reduce the given expressions to a list of unique Vars used. For |
| * example, GROUP BY a, a + b is treated the same as GROUP BY a, b. |
| * It is clearly correct not to count the same Var more than once. |
| * It is also reasonable to treat f(x) the same as x: f() cannot |
| * increase the number of distinct values (unless it is volatile, |
| * which we consider unlikely for grouping), but it probably won't |
| * reduce the number of distinct values much either. |
| * As a special case, if a GROUP BY expression can be matched to an |
| * expressional index for which we have statistics, then we treat the |
| * whole expression as though it were just a Var. |
| * 2. If the list contains Vars of different relations that are known equal |
| * due to equijoin clauses, then drop all but one of the Vars from each |
| * known-equal set, keeping the one with smallest estimated # of values |
| * (since the extra values of the others can't appear in joined rows). |
| * Note the reason we only consider Vars of different relations is that |
| * if we considered ones of the same rel, we'd be double-counting the |
| * restriction selectivity of the equality in the next step. |
| * 3. For Vars within a single source rel, we multiply together the numbers |
| * of values, clamp to the number of rows in the rel (divided by 10 if |
| * more than one Var), and then multiply by the selectivity of the |
| * restriction clauses for that rel. When there's more than one Var, |
| * the initial product is probably too high (it's the worst case) but |
| * clamping to a fraction of the rel's rows seems to be a helpful |
| * heuristic for not letting the estimate get out of hand. (The factor |
| * of 10 is derived from pre-Postgres-7.4 practice.) Multiplying |
| * by the restriction selectivity is effectively assuming that the |
| * restriction clauses are independent of the grouping, which is a crummy |
| * assumption, but it's hard to do better. |
| * 4. If there are Vars from multiple rels, we repeat step 3 for each such |
| * rel, and multiply the results together. |
| * Note that rels not containing grouped Vars are ignored completely, as are |
| * join clauses other than the equijoin clauses used in step 2. Such rels |
| * cannot increase the number of groups, and we assume such clauses do not |
| * reduce the number either (somewhat bogus, but we don't have the info to |
| * do better). |
| */ |
| double |
| estimate_num_groups(PlannerInfo *root, List *groupExprs, double input_rows) |
| { |
| List *varinfos = NIL; |
| double numdistinct; |
| ListCell *l; |
| |
| /* We should not be called unless query has GROUP BY (or DISTINCT) */ |
| Assert(groupExprs != NIL); |
| |
| /* |
| * Steps 1/2: find the unique Vars used, treating an expression as a Var |
| * if we can find stats for it. For each one, record the statistical |
| * estimate of number of distinct values (total in its table, without |
| * regard for filtering). |
| */ |
| foreach(l, groupExprs) |
| { |
| Node *groupexpr = (Node *) lfirst(l); |
| VariableStatData vardata; |
| List *varshere; |
| ListCell *l2; |
| |
| /* |
| * If examine_variable is able to deduce anything about the GROUP BY |
| * expression, treat it as a single variable even if it's really more |
| * complicated. |
| */ |
| examine_variable(root, groupexpr, 0, &vardata); |
| |
| if (HeapTupleIsValid(getStatsTuple(&vardata)) |
| || vardata.isunique) |
| { |
| varinfos = add_unique_group_var(root, varinfos, |
| groupexpr, &vardata); |
| ReleaseVariableStats(vardata); |
| continue; |
| } |
| ReleaseVariableStats(vardata); |
| |
| /* |
| * Else pull out the component Vars |
| */ |
| varshere = pull_var_clause(groupexpr, false); |
| |
| /* |
| * If we find any variable-free GROUP BY item, then either it is a |
| * constant (and we can ignore it) or it contains a volatile function; |
| * in the latter case we punt and assume that each input row will |
| * yield a distinct group. |
| */ |
| if (varshere == NIL) |
| { |
| if (contain_volatile_functions(groupexpr)) |
| return input_rows; |
| continue; |
| } |
| |
| /* |
| * Else add variables to varinfos list |
| */ |
| foreach(l2, varshere) |
| { |
| Node *var = (Node *) lfirst(l2); |
| |
| examine_variable(root, var, 0, &vardata); |
| varinfos = add_unique_group_var(root, varinfos, var, &vardata); |
| ReleaseVariableStats(vardata); |
| } |
| } |
| |
| /* If now no Vars, we must have an all-constant GROUP BY list. */ |
| if (varinfos == NIL) |
| return 1.0; |
| |
| /* |
| * Steps 3/4: group Vars by relation and estimate total numdistinct. |
| * |
| * For each iteration of the outer loop, we process the frontmost Var in |
| * varinfos, plus all other Vars in the same relation. We remove these |
| * Vars from the newvarinfos list for the next iteration. This is the |
| * easiest way to group Vars of same rel together. |
| */ |
| numdistinct = 1.0; |
| |
| do |
| { |
| GroupVarInfo *varinfo1 = (GroupVarInfo *) linitial(varinfos); |
| RelOptInfo *rel = varinfo1->rel; |
| double reldistinct = varinfo1->ndistinct; |
| double relmaxndistinct = reldistinct; |
| int relvarcount = 1; |
| List *newvarinfos = NIL; |
| |
| /* |
| * Get the product of numdistinct estimates of the Vars for this rel. |
| * Also, construct new varinfos list of remaining Vars. |
| */ |
| for_each_cell(l, lnext(list_head(varinfos))) |
| { |
| GroupVarInfo *varinfo2 = (GroupVarInfo *) lfirst(l); |
| |
| if (varinfo2->rel == varinfo1->rel) |
| { |
| reldistinct *= varinfo2->ndistinct; |
| if (relmaxndistinct < varinfo2->ndistinct) |
| relmaxndistinct = varinfo2->ndistinct; |
| relvarcount++; |
| } |
| else |
| { |
| /* not time to process varinfo2 yet */ |
| newvarinfos = lcons(varinfo2, newvarinfos); |
| } |
| } |
| |
| /* |
| * Sanity check --- don't divide by zero if empty relation. |
| */ |
| Assert(rel->reloptkind == RELOPT_BASEREL || |
| (rel->reloptkind == RELOPT_OTHER_MEMBER_REL && |
| rel->rtekind == RTE_RELATION)); |
| if (rel->tuples > 0) |
| { |
| /* |
| * Clamp to size of rel, or size of rel / 10 if multiple Vars. The |
| * fudge factor is because the Vars are probably correlated but we |
| * don't know by how much. We should never clamp to less than the |
| * largest ndistinct value for any of the Vars, though, since |
| * there will surely be at least that many groups. |
| */ |
| double clamp = rel->tuples; |
| |
| if (relvarcount > 1) |
| { |
| clamp *= 0.1; |
| if (clamp < relmaxndistinct) |
| { |
| clamp = relmaxndistinct; |
| /* for sanity in case some ndistinct is too large: */ |
| if (clamp > rel->tuples) |
| clamp = rel->tuples; |
| } |
| } |
| if (reldistinct > clamp) |
| reldistinct = clamp; |
| |
| /* |
| * Multiply by restriction selectivity. |
| */ |
| reldistinct *= rel->rows / rel->tuples; |
| |
| /* |
| * Update estimate of total distinct groups. |
| */ |
| numdistinct *= reldistinct; |
| } |
| |
| varinfos = newvarinfos; |
| } while (varinfos != NIL); |
| |
| numdistinct = ceil(numdistinct); |
| |
| /* Guard against out-of-range answers */ |
| if (numdistinct > input_rows) |
| numdistinct = input_rows; |
| if (numdistinct < 1.0) |
| numdistinct = 1.0; |
| |
| return numdistinct; |
| } |
| |
| /* |
| * Estimate hash bucketsize fraction (ie, number of entries in a bucket |
| * divided by total tuples in relation) if the specified expression is used |
| * as a hash key. |
| * |
| * XXX This is really pretty bogus since we're effectively assuming that the |
| * distribution of hash keys will be the same after applying restriction |
| * clauses as it was in the underlying relation. However, we are not nearly |
| * smart enough to figure out how the restrict clauses might change the |
| * distribution, so this will have to do for now. |
| * |
| * We are passed the number of buckets the executor will use for the given |
| * input relation. If the data were perfectly distributed, with the same |
| * number of tuples going into each available bucket, then the bucketsize |
| * fraction would be 1/nbuckets. But this happy state of affairs will occur |
| * only if (a) there are at least nbuckets distinct data values, and (b) |
| * we have a not-too-skewed data distribution. Otherwise the buckets will |
| * be nonuniformly occupied. If the other relation in the join has a key |
| * distribution similar to this one's, then the most-loaded buckets are |
| * exactly those that will be probed most often. Therefore, the "average" |
| * bucket size for costing purposes should really be taken as something close |
| * to the "worst case" bucket size. We try to estimate this by adjusting the |
| * fraction if there are too few distinct data values, and then scaling up |
| * by the ratio of the most common value's frequency to the average frequency. |
| * |
| * If no statistics are available, use a default estimate of 0.1. This will |
| * discourage use of a hash rather strongly if the inner relation is large, |
| * which is what we want. We do not want to hash unless we know that the |
| * inner rel is well-dispersed (or the alternatives seem much worse). |
| */ |
| Selectivity |
| estimate_hash_bucketsize(PlannerInfo *root, Node *hashkey, double nbuckets) |
| { |
| VariableStatData vardata; |
| double estfract, |
| ndistinct, |
| stanullfrac, |
| mcvfreq, |
| avgfreq; |
| float4 *numbers; |
| int nnumbers; |
| |
| examine_variable(root, hashkey, 0, &vardata); |
| |
| /* Get number of distinct values and fraction that are null */ |
| ndistinct = get_variable_numdistinct(&vardata); |
| |
| if (HeapTupleIsValid(getStatsTuple(&vardata))) |
| { |
| HeapTuple tp = getStatsTuple(&vardata); |
| Form_pg_statistic stats; |
| |
| stats = (Form_pg_statistic) GETSTRUCT(tp); |
| stanullfrac = stats->stanullfrac; |
| } |
| else |
| { |
| /* |
| * Believe a default ndistinct only if it came from stats. Otherwise |
| * punt and return 0.1, per comments above. |
| */ |
| if (ndistinct == DEFAULT_NUM_DISTINCT) |
| { |
| ReleaseVariableStats(vardata); |
| return (Selectivity) 0.1; |
| } |
| |
| stanullfrac = 0.0; |
| } |
| |
| /* Compute avg freq of all distinct data values in raw relation */ |
| avgfreq = (1.0 - stanullfrac) / ndistinct; |
| |
| /* |
| * Adjust ndistinct to account for restriction clauses. Observe we are |
| * assuming that the data distribution is affected uniformly by the |
| * restriction clauses! |
| * |
| * XXX Possibly better way, but much more expensive: multiply by |
| * selectivity of rel's restriction clauses that mention the target Var. |
| */ |
| if (vardata.rel) |
| ndistinct *= vardata.rel->rows / vardata.rel->tuples; |
| |
| /* |
| * Initial estimate of bucketsize fraction is 1/nbuckets as long as the |
| * number of buckets is less than the expected number of distinct values; |
| * otherwise it is 1/ndistinct. |
| */ |
| if (ndistinct > nbuckets) |
| estfract = 1.0 / nbuckets; |
| else |
| estfract = 1.0 / ndistinct; |
| |
| /* |
| * Look up the frequency of the most common value, if available. |
| */ |
| mcvfreq = 0.0; |
| |
| if (HeapTupleIsValid(getStatsTuple(&vardata))) |
| { |
| HeapTuple tp = getStatsTuple(&vardata); |
| |
| if (get_attstatsslot(tp, |
| vardata.atttype, vardata.atttypmod, |
| STATISTIC_KIND_MCV, InvalidOid, |
| NULL, NULL, &numbers, &nnumbers)) |
| { |
| /* |
| * The first MCV stat is for the most common value. |
| */ |
| if (nnumbers > 0) |
| mcvfreq = numbers[0]; |
| free_attstatsslot(vardata.atttype, NULL, 0, |
| numbers, nnumbers); |
| } |
| } |
| |
| /* |
| * Adjust estimated bucketsize upward to account for skewed distribution. |
| */ |
| if (avgfreq > 0.0 && mcvfreq > avgfreq) |
| estfract *= mcvfreq / avgfreq; |
| |
| /* |
| * Clamp bucketsize to sane range (the above adjustment could easily |
| * produce an out-of-range result). We set the lower bound a little above |
| * zero, since zero isn't a very sane result. |
| */ |
| if (estfract < 1.0e-6) |
| estfract = 1.0e-6; |
| else if (estfract > 1.0) |
| estfract = 1.0; |
| |
| ReleaseVariableStats(vardata); |
| |
| return (Selectivity) estfract; |
| } |
| |
| |
| /*------------------------------------------------------------------------- |
| * |
| * Support routines |
| * |
| *------------------------------------------------------------------------- |
| */ |
| |
| /* |
| * convert_to_scalar |
| * Convert non-NULL values of the indicated types to the comparison |
| * scale needed by scalarineqsel(). |
| * Returns "true" if successful. |
| * |
| * XXX this routine is a hack: ideally we should look up the conversion |
| * subroutines in pg_type. |
| * |
| * All numeric datatypes are simply converted to their equivalent |
| * "double" values. (NUMERIC values that are outside the range of "double" |
| * are clamped to +/- HUGE_VAL.) |
| * |
| * String datatypes are converted to have hi and lo bound be constants, with |
| * the scaledvalue equally either hi or lo, depending on the value of isgt |
| * (done so that the caller will include the entire bucket in the final |
| * computed selectivity, even after inverting for the isgt case) |
| * |
| * The bytea datatype is just enough different from strings that it has |
| * to be treated separately. |
| * |
| * The several datatypes representing absolute times are all converted |
| * to Timestamp, which is actually a double, and then we just use that |
| * double value. Note this will give correct results even for the "special" |
| * values of Timestamp, since those are chosen to compare correctly; |
| * see timestamp_cmp. |
| * |
| * The several datatypes representing relative times (intervals) are all |
| * converted to measurements expressed in seconds. |
| * |
| * isgt can be used by datatypes which cannot interpolate and instead must |
| * return an appropriate default |
| * |
| */ |
| static bool |
| convert_to_scalar(Datum value, Oid valuetypid, double *scaledvalue, |
| Datum lobound, Datum hibound, Oid boundstypid, |
| double *scaledlobound, double *scaledhibound, |
| bool isgt) |
| { |
| /* |
| * Both the valuetypid and the boundstypid should exactly match the |
| * declared input type(s) of the operator we are invoked for, so we just |
| * error out if either is not recognized. |
| * |
| * XXX The histogram we are interpolating between points of could belong |
| * to a column that's only binary-compatible with the declared type. In |
| * essence we are assuming that the semantics of binary-compatible types |
| * are enough alike that we can use a histogram generated with one type's |
| * operators to estimate selectivity for the other's. This is outright |
| * wrong in some cases --- in particular signed versus unsigned |
| * interpretation could trip us up. But it's useful enough in the |
| * majority of cases that we do it anyway. Should think about more |
| * rigorous ways to do it. |
| */ |
| switch (valuetypid) |
| { |
| /* |
| * Built-in numeric types |
| */ |
| case BOOLOID: |
| case INT2OID: |
| case INT4OID: |
| case INT8OID: |
| case FLOAT4OID: |
| case FLOAT8OID: |
| case NUMERICOID: |
| case OIDOID: |
| case REGPROCOID: |
| case REGPROCEDUREOID: |
| case REGOPEROID: |
| case REGOPERATOROID: |
| case REGCLASSOID: |
| case REGTYPEOID: |
| *scaledvalue = convert_numeric_to_scalar(value, valuetypid); |
| *scaledlobound = convert_numeric_to_scalar(lobound, boundstypid); |
| *scaledhibound = convert_numeric_to_scalar(hibound, boundstypid); |
| return true; |
| |
| /* |
| * Built-in string types |
| */ |
| case CHAROID: |
| case BPCHAROID: |
| case VARCHAROID: |
| case TEXTOID: |
| case NAMEOID: |
| { |
| *scaledlobound = 1; |
| *scaledhibound = 2; |
| *scaledvalue = isgt ? 1 : 2; |
| return true; |
| } |
| |
| /* |
| * Built-in bytea type |
| */ |
| case BYTEAOID: |
| { |
| convert_bytea_to_scalar(value, scaledvalue, |
| lobound, scaledlobound, |
| hibound, scaledhibound); |
| return true; |
| } |
| |
| /* |
| * Built-in time types |
| */ |
| case TIMESTAMPOID: |
| case TIMESTAMPTZOID: |
| case ABSTIMEOID: |
| case DATEOID: |
| case INTERVALOID: |
| case RELTIMEOID: |
| case TINTERVALOID: |
| case TIMEOID: |
| case TIMETZOID: |
| *scaledvalue = convert_timevalue_to_scalar(value, valuetypid); |
| *scaledlobound = convert_timevalue_to_scalar(lobound, boundstypid); |
| *scaledhibound = convert_timevalue_to_scalar(hibound, boundstypid); |
| return true; |
| |
| /* |
| * Built-in network types |
| */ |
| case INETOID: |
| case CIDROID: |
| case MACADDROID: |
| *scaledvalue = convert_network_to_scalar(value, valuetypid); |
| *scaledlobound = convert_network_to_scalar(lobound, boundstypid); |
| *scaledhibound = convert_network_to_scalar(hibound, boundstypid); |
| return true; |
| } |
| /* Don't know how to convert */ |
| *scaledvalue = *scaledlobound = *scaledhibound = 0; |
| return false; |
| } |
| |
| /* |
| * Do convert_to_scalar()'s work for any numeric data type. |
| */ |
| static double |
| convert_numeric_to_scalar(Datum value, Oid typid) |
| { |
| switch (typid) |
| { |
| case BOOLOID: |
| return (double) DatumGetBool(value); |
| case INT2OID: |
| return (double) DatumGetInt16(value); |
| case INT4OID: |
| return (double) DatumGetInt32(value); |
| case INT8OID: |
| return (double) DatumGetInt64(value); |
| case FLOAT4OID: |
| return (double) DatumGetFloat4(value); |
| case FLOAT8OID: |
| return (double) DatumGetFloat8(value); |
| case NUMERICOID: |
| /* Note: out-of-range values will be clamped to +-HUGE_VAL */ |
| return (double) |
| DatumGetFloat8(DirectFunctionCall1(numeric_float8_no_overflow, |
| value)); |
| case OIDOID: |
| case REGPROCOID: |
| case REGPROCEDUREOID: |
| case REGOPEROID: |
| case REGOPERATOROID: |
| case REGCLASSOID: |
| case REGTYPEOID: |
| /* we can treat OIDs as integers... */ |
| return (double) DatumGetObjectId(value); |
| } |
| |
| /* |
| * Can't get here unless someone tries to use scalarltsel/scalargtsel on |
| * an operator with one numeric and one non-numeric operand. |
| */ |
| elog(ERROR, "unsupported type: %u", typid); |
| return 0; |
| } |
| |
| /* |
| * Do convert_to_scalar()'s work for any bytea data type. |
| * |
| * Very similar to the old convert_string_to_scalar except we can't assume |
| * null-termination and therefore pass explicit lengths around. |
| * |
| * Also, assumptions about likely "normal" ranges of characters have been |
| * removed - a data range of 0..255 is always used, for now. (Perhaps |
| * someday we will add information about actual byte data range to |
| * pg_statistic.) |
| */ |
| static void |
| convert_bytea_to_scalar(Datum value, |
| double *scaledvalue, |
| Datum lobound, |
| double *scaledlobound, |
| Datum hibound, |
| double *scaledhibound) |
| { |
| int rangelo, |
| rangehi, |
| valuelen = VARSIZE(DatumGetPointer(value)) - VARHDRSZ, |
| loboundlen = VARSIZE(DatumGetPointer(lobound)) - VARHDRSZ, |
| hiboundlen = VARSIZE(DatumGetPointer(hibound)) - VARHDRSZ, |
| i, |
| minlen; |
| unsigned char *valstr = (unsigned char *) VARDATA(DatumGetPointer(value)), |
| *lostr = (unsigned char *) VARDATA(DatumGetPointer(lobound)), |
| *histr = (unsigned char *) VARDATA(DatumGetPointer(hibound)); |
| |
| /* |
| * Assume bytea data is uniformly distributed across all byte values. |
| */ |
| rangelo = 0; |
| rangehi = 255; |
| |
| /* |
| * Now strip any common prefix of the three strings. |
| */ |
| minlen = Min(Min(valuelen, loboundlen), hiboundlen); |
| for (i = 0; i < minlen; i++) |
| { |
| if (*lostr != *histr || *lostr != *valstr) |
| break; |
| lostr++, histr++, valstr++; |
| loboundlen--, hiboundlen--, valuelen--; |
| } |
| |
| /* |
| * Now we can do the conversions. |
| */ |
| *scaledvalue = convert_one_bytea_to_scalar(valstr, valuelen, rangelo, rangehi); |
| *scaledlobound = convert_one_bytea_to_scalar(lostr, loboundlen, rangelo, rangehi); |
| *scaledhibound = convert_one_bytea_to_scalar(histr, hiboundlen, rangelo, rangehi); |
| } |
| |
| static double |
| convert_one_bytea_to_scalar(unsigned char *value, int valuelen, |
| int rangelo, int rangehi) |
| { |
| double num, |
| denom, |
| base; |
| |
| if (valuelen <= 0) |
| return 0.0; /* empty string has scalar value 0 */ |
| |
| /* |
| * Since base is 256, need not consider more than about 10 chars (even |
| * this many seems like overkill) |
| */ |
| if (valuelen > 10) |
| valuelen = 10; |
| |
| /* Convert initial characters to fraction */ |
| base = rangehi - rangelo + 1; |
| num = 0.0; |
| denom = base; |
| while (valuelen-- > 0) |
| { |
| int ch = *value++; |
| |
| if (ch < rangelo) |
| ch = rangelo - 1; |
| else if (ch > rangehi) |
| ch = rangehi + 1; |
| num += ((double) (ch - rangelo)) / denom; |
| denom *= base; |
| } |
| |
| return num; |
| } |
| |
| /* |
| * Do convert_to_scalar()'s work for any timevalue data type. |
| */ |
| double |
| convert_timevalue_to_scalar(Datum value, Oid typid) |
| { |
| switch (typid) |
| { |
| case TIMESTAMPOID: |
| return DatumGetTimestamp(value); |
| case TIMESTAMPTZOID: |
| return DatumGetTimestampTz(value); |
| case ABSTIMEOID: |
| return DatumGetTimestamp(DirectFunctionCall1(abstime_timestamp, |
| value)); |
| case DATEOID: |
| return DatumGetTimestamp(DirectFunctionCall1(date_timestamp, |
| value)); |
| case INTERVALOID: |
| { |
| Interval *interval = DatumGetIntervalP(value); |
| |
| /* |
| * Convert the month part of Interval to days using assumed |
| * average month length of 365.25/12.0 days. Not too |
| * accurate, but plenty good enough for our purposes. |
| */ |
| #ifdef HAVE_INT64_TIMESTAMP |
| return interval->time + interval->day * (double) USECS_PER_DAY + |
| interval->month * ((DAYS_PER_YEAR / (double) MONTHS_PER_YEAR) * USECS_PER_DAY); |
| #else |
| return interval->time + interval->day * SECS_PER_DAY + |
| interval->month * ((DAYS_PER_YEAR / (double) MONTHS_PER_YEAR) * (double) SECS_PER_DAY); |
| #endif |
| } |
| case RELTIMEOID: |
| #ifdef HAVE_INT64_TIMESTAMP |
| return (DatumGetRelativeTime(value) * 1000000.0); |
| #else |
| return DatumGetRelativeTime(value); |
| #endif |
| case TINTERVALOID: |
| { |
| TimeInterval tinterval = DatumGetTimeInterval(value); |
| |
| #ifdef HAVE_INT64_TIMESTAMP |
| if (tinterval->status != 0) |
| return ((tinterval->data[1] - tinterval->data[0]) * 1000000.0); |
| #else |
| if (tinterval->status != 0) |
| return tinterval->data[1] - tinterval->data[0]; |
| #endif |
| return 0; /* for lack of a better idea */ |
| } |
| case TIMEOID: |
| return DatumGetTimeADT(value); |
| case TIMETZOID: |
| { |
| TimeTzADT *timetz = DatumGetTimeTzADTP(value); |
| |
| /* use GMT-equivalent time */ |
| #ifdef HAVE_INT64_TIMESTAMP |
| return (double) (timetz->time + (timetz->zone * 1000000.0)); |
| #else |
| return (double) (timetz->time + timetz->zone); |
| #endif |
| } |
| } |
| |
| /* |
| * Can't get here unless someone tries to use scalarltsel/scalargtsel on |
| * an operator with one timevalue and one non-timevalue operand. |
| */ |
| elog(ERROR, "unsupported type: %u", typid); |
| return 0; |
| } |
| |
| |
| /* |
| * get_restriction_variable |
| * Examine the args of a restriction clause to see if it's of the |
| * form (variable op pseudoconstant) or (pseudoconstant op variable), |
| * where "variable" could be either a Var or an expression in vars of a |
| * single relation. If so, extract information about the variable, |
| * and also indicate which side it was on and the other argument. |
| * |
| * Inputs: |
| * root: the planner info |
| * args: clause argument list |
| * varRelid: see specs for restriction selectivity functions |
| * |
| * Outputs: (these are valid only if TRUE is returned) |
| * *vardata: gets information about variable (see examine_variable) |
| * *other: gets other clause argument, aggressively reduced to a constant |
| * *varonleft: set TRUE if variable is on the left, FALSE if on the right |
| * |
| * Returns TRUE if a variable is identified, otherwise FALSE. |
| * |
| * Note: if there are Vars on both sides of the clause, we must fail, because |
| * callers are expecting that the other side will act like a pseudoconstant. |
| */ |
| bool |
| get_restriction_variable(PlannerInfo *root, List *args, int varRelid, |
| VariableStatData *vardata, Node **other, |
| bool *varonleft) |
| { |
| Node *left, |
| *right; |
| VariableStatData rdata; |
| |
| /* Fail if not a binary opclause (probably shouldn't happen) */ |
| if (list_length(args) != 2) |
| return false; |
| |
| left = (Node *) linitial(args); |
| right = (Node *) lsecond(args); |
| |
| /* |
| * Examine both sides. Note that when varRelid is nonzero, Vars of other |
| * relations will be treated as pseudoconstants. |
| */ |
| examine_variable(root, left, varRelid, vardata); |
| examine_variable(root, right, varRelid, &rdata); |
| |
| /* |
| * If one side is a variable and the other not, we win. |
| */ |
| if (vardata->rel && rdata.rel == NULL) |
| { |
| *varonleft = true; |
| *other = estimate_expression_value(root, rdata.var); |
| /* Assume we need no ReleaseVariableStats(rdata) here */ |
| return true; |
| } |
| |
| if (vardata->rel == NULL && rdata.rel) |
| { |
| *varonleft = false; |
| *other = estimate_expression_value(root, vardata->var); |
| /* Assume we need no ReleaseVariableStats(*vardata) here */ |
| *vardata = rdata; |
| return true; |
| } |
| |
| /* Ooops, clause has wrong structure (probably var op var) */ |
| ReleaseVariableStats(*vardata); |
| ReleaseVariableStats(rdata); |
| |
| return false; |
| } |
| |
| /* |
| * get_join_variables |
| * Apply examine_variable() to each side of a join clause. |
| */ |
| void |
| get_join_variables(PlannerInfo *root, List *args, |
| VariableStatData *vardata1, VariableStatData *vardata2) |
| { |
| Node *left, |
| *right; |
| |
| if (list_length(args) != 2) |
| elog(ERROR, "join operator should take two arguments"); |
| |
| left = (Node *) linitial(args); |
| right = (Node *) lsecond(args); |
| |
| examine_variable(root, left, 0, vardata1); |
| examine_variable(root, right, 0, vardata2); |
| } |
| |
| /* |
| * This method returns a pointer to the largest child relation for an inherited (incl partitioned) |
| * relation. If there are multiple levels in the hierarchy, we delve down recursively till we |
| * find the largest (as determined from the path structure). |
| * Input: a partitioned table |
| * Output: largest child partition. If there are no child partition because all of them have been eliminated, then |
| * returns NULL. |
| */ |
| static RelOptInfo* largest_child_relation(PlannerInfo *root, RelOptInfo *rel) |
| { |
| AppendPath *append_path = NULL; |
| ListCell *subpath_lc = NULL; |
| RelOptInfo *largest_child_in_subpath = NULL; |
| double max_rows = -1.0; |
| |
| Assert(IsA(rel->cheapest_total_path, AppendPath)); |
| |
| append_path = (AppendPath *) rel->cheapest_total_path; |
| |
| foreach(subpath_lc, append_path->subpaths) |
| { |
| RelOptInfo *candidate_child = NULL; |
| Path *subpath = lfirst(subpath_lc); |
| |
| if (IsA(subpath, AppendPath)) |
| { |
| candidate_child = largest_child_relation(root, subpath->parent); |
| } |
| else |
| { |
| candidate_child = subpath->parent; |
| } |
| |
| if (candidate_child && candidate_child->rows > max_rows) |
| { |
| max_rows = candidate_child->rows; |
| largest_child_in_subpath = candidate_child; |
| } |
| } |
| |
| return largest_child_in_subpath; |
| } |
| |
| /* |
| * The purpose of this method is to make the statistics (on a specific column) of a child partition |
| * representative of the parent relation. This entails the following assumptions: |
| * 1. if ndistinct<=-1.0 in child partition, the column is a unique column in the child partition. We |
| * expect the column to remain distinct in the master as well. |
| * 2. if -1.0 < ndistinct < 0.0, the absolute number of ndistinct values in the child partition is a fraction |
| * of the number of rows in the partition. We expect that the absolute number of ndistinct in the master |
| * to stay the same. Therefore, we convert this to a positive number. |
| * The method get_variable_numdistinct will multiply this by the number of tuples in the master relation. |
| * 3. if ndistinct is positive, it indicates a small absolute number of distinct values. We expect these |
| * values to be repeated in all partitions. Therefore, we expect no change in the ndistinct in the master. |
| * |
| * Input: |
| * statsTuple, which is a heaptuple representing statistics on a child relation. It expects statstuple to be non-null. |
| * scalefactor, which is in the range (0.0,1.0] |
| * |
| * Output: |
| * This method modifies the tuple passed to it. |
| */ |
| static void inline adjust_partition_table_statistic_for_parent(HeapTuple statsTuple, double childtuples) |
| { |
| Form_pg_statistic stats; |
| |
| Assert(HeapTupleIsValid(statsTuple)); |
| |
| stats = (Form_pg_statistic) GETSTRUCT(statsTuple); |
| |
| if (stats->stadistinct <= -1.0) |
| { |
| /* |
| * Case 1 as described above. |
| */ |
| |
| return; |
| } |
| else if (stats->stadistinct < 0.0) |
| { |
| /* |
| * Case 2 as described above. |
| */ |
| |
| stats->stadistinct = ((double) -1.0) * stats->stadistinct * childtuples; |
| } |
| else |
| { |
| /** |
| * Case 3 as described above. |
| */ |
| |
| return; |
| } |
| } |
| |
| /* |
| * examine_variable |
| * Try to look up statistical data about an expression. |
| * Fill in a VariableStatData struct to describe the expression. |
| * |
| * Inputs: |
| * root: the planner info |
| * node: the expression tree to examine |
| * varRelid: see specs for restriction selectivity functions |
| * |
| * Outputs: *vardata is filled as follows: |
| * var: the input expression (with any binary relabeling stripped, if |
| * it is or contains a variable; but otherwise the type is preserved) |
| * rel: RelOptInfo for relation containing variable; NULL if expression |
| * contains no Vars (NOTE this could point to a RelOptInfo of a |
| * subquery, not one in the current query). |
| * statsTuple: the pg_statistic entry for the variable, if one exists; |
| * otherwise NULL. |
| * vartype: exposed type of the expression; this should always match |
| * the declared input type of the operator we are estimating for. |
| * atttype, atttypmod: type data to pass to get_attstatsslot(). This is |
| * commonly the same as the exposed type of the variable argument, |
| * but can be different in binary-compatible-type cases. |
| * |
| * Caller is responsible for doing ReleaseVariableStats() before exiting. |
| */ |
| void |
| examine_variable(PlannerInfo *root, Node *node, int varRelid, |
| VariableStatData *vardata) |
| { |
| Node *basenode; |
| Relids varnos; |
| RelOptInfo *onerel; |
| |
| /* Make sure we don't return dangling pointers in vardata */ |
| MemSet(vardata, 0, sizeof(VariableStatData)); |
| |
| /* Save the exposed type of the expression */ |
| vardata->vartype = exprType(node); |
| |
| vardata->numdistinctFromPrimaryKey = -1.0; /* ignore by default*/ |
| |
| /* Look inside any binary-compatible relabeling */ |
| |
| if (IsA(node, RelabelType)) |
| basenode = (Node *) ((RelabelType *) node)->arg; |
| else |
| basenode = node; |
| |
| /* Fast path for a simple Var */ |
| |
| if (IsA(basenode, Var) && |
| (varRelid == 0 || varRelid == ((Var *) basenode)->varno)) |
| { |
| Var *var = (Var *) basenode; |
| RangeTblEntry *rte; |
| |
| vardata->var = basenode; /* return Var without relabeling */ |
| vardata->rel = find_base_rel(root, var->varno); |
| vardata->atttype = var->vartype; |
| vardata->atttypmod = var->vartypmod; |
| |
| rte = rt_fetch(var->varno, root->parse->rtable); |
| |
| /* |
| * If this attribute has a foreign key relationship, then first look |
| * at primary key statistics. If there exist stats on that attribute, |
| * we utilize those. If not, continue. |
| */ |
| |
| if (gp_statistics_use_fkeys) |
| { |
| Oid pkrelid = InvalidOid; |
| AttrNumber pkattno = -1; |
| |
| if (ConstraintGetPrimaryKeyOf(rte->relid, var->varattno, &pkrelid, &pkattno)) |
| { |
| cqContext *relcqCtx; |
| HeapTuple pkStatsTuple; |
| |
| /* SELECT reltuples FROM pg_class */ |
| |
| relcqCtx = caql_beginscan( |
| NULL, |
| cql("SELECT * FROM pg_class " |
| " WHERE oid = :1 ", |
| ObjectIdGetDatum(pkrelid))); |
| |
| pkStatsTuple = caql_getnext(relcqCtx); |
| |
| if (HeapTupleIsValid(pkStatsTuple)) |
| { |
| Form_pg_class classForm = (Form_pg_class) GETSTRUCT(pkStatsTuple); |
| if (classForm->reltuples > 0) |
| { |
| vardata->numdistinctFromPrimaryKey = classForm->reltuples; |
| } |
| } |
| |
| caql_endscan(relcqCtx); |
| } |
| } |
| if (rte->inh) |
| { |
| /* |
| * If gp_statistics_pullup_from_child_partition is set, we attempt to pull up statistics from |
| * the largest child partition in an inherited or a partitioned table. |
| */ |
| if (gp_statistics_pullup_from_child_partition && |
| vardata->rel->cheapest_total_path != NULL) |
| { |
| RelOptInfo *childrel = largest_child_relation(root, vardata->rel); |
| vardata->statscqCtx = NULL; |
| |
| if (childrel) |
| { |
| RangeTblEntry *child_rte = NULL; |
| |
| child_rte = rt_fetch(childrel->relid, root->parse->rtable); |
| |
| Assert(child_rte != NULL); |
| |
| /* |
| * Get statistics from the child partition. |
| */ |
| vardata->statscqCtx = caql_beginscan |
| ( |
| NULL, |
| cql("SELECT * FROM pg_statistic " |
| " WHERE starelid = :1 " |
| " AND staattnum = :2 ", |
| ObjectIdGetDatum(child_rte->relid), |
| Int16GetDatum(var->varattno)) |
| ); |
| |
| (void) caql_getnext(vardata->statscqCtx); |
| |
| if (NULL != vardata->statscqCtx && NULL != vardata->statscqCtx->cq_lasttup) |
| { |
| adjust_partition_table_statistic_for_parent(vardata->statscqCtx->cq_lasttup, childrel->tuples); |
| } |
| } |
| } |
| } |
| else if (rte->rtekind == RTE_RELATION) |
| { |
| vardata->statscqCtx = caql_beginscan( |
| NULL, |
| cql("SELECT * FROM pg_statistic " |
| " WHERE starelid = :1 " |
| " AND staattnum = :2 ", |
| ObjectIdGetDatum(rte->relid), |
| Int16GetDatum(var->varattno))); |
| |
| /* fetch the tuple */ |
| (void) caql_getnext(vardata->statscqCtx); |
| } |
| else |
| { |
| /* |
| * XXX This means the Var comes from a JOIN or sub-SELECT. Later |
| * add code to dig down into the join etc and see if we can trace |
| * the variable to something with stats. (But beware of |
| * sub-SELECTs with DISTINCT/GROUP BY/etc. Perhaps there are no |
| * cases where this would really be useful, because we'd have |
| * flattened the subselect if it is??) |
| */ |
| } |
| |
| return; |
| } |
| |
| /* |
| * Okay, it's a more complicated expression. Determine variable |
| * membership. Note that when varRelid isn't zero, only vars of that |
| * relation are considered "real" vars. |
| */ |
| varnos = pull_varnos(basenode); |
| |
| onerel = NULL; |
| |
| switch (bms_membership(varnos)) |
| { |
| case BMS_EMPTY_SET: |
| /* No Vars at all ... must be pseudo-constant clause */ |
| break; |
| case BMS_SINGLETON: |
| if (varRelid == 0 || bms_is_member(varRelid, varnos)) |
| { |
| onerel = find_base_rel(root, |
| (varRelid ? varRelid : bms_singleton_member(varnos))); |
| vardata->rel = onerel; |
| node = basenode; /* strip any relabeling */ |
| } |
| /* else treat it as a constant */ |
| break; |
| case BMS_MULTIPLE: |
| if (varRelid == 0) |
| { |
| /* treat it as a variable of a join relation */ |
| vardata->rel = find_join_rel(root, varnos); |
| node = basenode; /* strip any relabeling */ |
| } |
| else if (bms_is_member(varRelid, varnos)) |
| { |
| /* ignore the vars belonging to other relations */ |
| vardata->rel = find_base_rel(root, varRelid); |
| node = basenode; /* strip any relabeling */ |
| /* note: no point in expressional-index search here */ |
| } |
| /* else treat it as a constant */ |
| break; |
| } |
| |
| bms_free(varnos); |
| |
| vardata->var = node; |
| vardata->atttype = exprType(node); |
| vardata->atttypmod = exprTypmod(node); |
| |
| if (onerel) |
| { |
| /* |
| * We have an expression in vars of a single relation. Try to match |
| * it to expressional index columns, in hopes of finding some |
| * statistics. |
| * |
| * XXX it's conceivable that there are multiple matches with different |
| * index opclasses; if so, we need to pick one that matches the |
| * operator we are estimating for. FIXME later. |
| */ |
| ListCell *ilist; |
| |
| foreach(ilist, onerel->indexlist) |
| { |
| IndexOptInfo *index = (IndexOptInfo *) lfirst(ilist); |
| ListCell *indexpr_item; |
| int pos; |
| |
| indexpr_item = list_head(index->indexprs); |
| if (indexpr_item == NULL) |
| continue; /* no expressions here... */ |
| |
| /* |
| * Ignore partial indexes since they probably don't reflect |
| * whole-relation statistics. Possibly reconsider this later. |
| */ |
| if (index->indpred) |
| continue; |
| |
| for (pos = 0; pos < index->ncolumns; pos++) |
| { |
| if (index->indexkeys[pos] == 0) |
| { |
| Node *indexkey; |
| |
| if (indexpr_item == NULL) |
| elog(ERROR, "too few entries in indexprs list"); |
| indexkey = (Node *) lfirst(indexpr_item); |
| if (indexkey && IsA(indexkey, RelabelType)) |
| indexkey = (Node *) ((RelabelType *) indexkey)->arg; |
| if (equal(node, indexkey)) |
| { |
| /* |
| * Found a match ... is it a unique index? Tests here |
| * should match has_unique_index(). |
| */ |
| if (index->unique && |
| index->ncolumns == 1 && |
| index->indpred == NIL) |
| vardata->isunique = true; |
| /* Has it got stats? */ |
| |
| vardata->statscqCtx = caql_beginscan( |
| NULL, |
| cql("SELECT * FROM pg_statistic " |
| " WHERE starelid = :1 " |
| " AND staattnum = :2 ", |
| ObjectIdGetDatum(index->indexoid), |
| Int16GetDatum(pos + 1))); |
| |
| /* fetch the tuple */ |
| (void) caql_getnext(vardata->statscqCtx); |
| |
| if (HeapTupleIsValid(getStatsTuple(vardata))) |
| break; |
| } |
| indexpr_item = lnext(indexpr_item); |
| } |
| } |
| if (HeapTupleIsValid(getStatsTuple(vardata))) |
| break; |
| } |
| } |
| } |
| |
| /** |
| * Input: vardata. Must be non-NULL. |
| */ |
| void ReleaseVariableStats(VariableStatData vardata) |
| { |
| if (vardata.statscqCtx) |
| caql_endscan(vardata.statscqCtx); |
| vardata.statscqCtx = NULL; |
| } |
| |
| /* |
| * get_variable_numdistinct |
| * Estimate the number of distinct values of a variable. |
| * |
| * vardata: results of examine_variable |
| * |
| * NB: be careful to produce an integral result, since callers may compare |
| * the result to exact integer counts. |
| */ |
| double |
| get_variable_numdistinct(VariableStatData *vardata) |
| { |
| double stadistinct; |
| double ntuples; |
| |
| /** |
| * If we have an estimate from the primary key, then that is the most accurate value. |
| */ |
| if (gp_statistics_use_fkeys && |
| vardata->numdistinctFromPrimaryKey > 0.0) |
| { |
| return vardata->numdistinctFromPrimaryKey; |
| } |
| |
| /* |
| * Determine the stadistinct value to use. There are cases where we can |
| * get an estimate even without a pg_statistic entry, or can get a better |
| * value than is in pg_statistic. |
| */ |
| if (HeapTupleIsValid(getStatsTuple(vardata))) |
| { |
| /* Use the pg_statistic entry */ |
| Form_pg_statistic stats; |
| HeapTuple tp = getStatsTuple(vardata); |
| |
| stats = (Form_pg_statistic) GETSTRUCT(tp); |
| stadistinct = stats->stadistinct; |
| } |
| else if (vardata->vartype == BOOLOID) |
| { |
| /* |
| * Special-case boolean columns: presumably, two distinct values. |
| * |
| * Are there any other datatypes we should wire in special estimates |
| * for? |
| */ |
| stadistinct = 2.0; |
| } |
| else |
| { |
| /* |
| * We don't keep statistics for system columns, but in some cases we |
| * can infer distinctness anyway. |
| */ |
| if (vardata->var && IsA(vardata->var, Var)) |
| { |
| switch (((Var *) vardata->var)->varattno) |
| { |
| case ObjectIdAttributeNumber: |
| case SelfItemPointerAttributeNumber: |
| stadistinct = -1.0; /* unique */ |
| break; |
| case TableOidAttributeNumber: |
| stadistinct = 1.0; /* only 1 value */ |
| break; |
| case GpSegmentIdAttributeNumber: /*CDB*/ |
| stadistinct = GetPlannerSegmentNum(); |
| break; |
| default: |
| stadistinct = 0.0; /* means "unknown" */ |
| break; |
| } |
| } |
| else |
| stadistinct = 0.0; /* means "unknown" */ |
| |
| /* |
| * XXX consider using estimate_num_groups on expressions? |
| */ |
| } |
| |
| /* |
| * If there is a unique index for the variable, assume it is unique no |
| * matter what pg_statistic says (the statistics could be out of date). |
| * Can skip search if we already think it's unique. |
| */ |
| if (stadistinct != -1.0) |
| { |
| if (vardata->isunique) |
| stadistinct = -1.0; |
| else if (vardata->var && IsA(vardata->var, Var) && |
| vardata->rel && |
| has_unique_index(vardata->rel, |
| ((Var *) vardata->var)->varattno)) |
| stadistinct = -1.0; |
| } |
| |
| /* |
| * If we had an absolute estimate, use that. |
| */ |
| if (stadistinct > 0.0) |
| return stadistinct; |
| |
| /* |
| * Otherwise we need to get the relation size; punt if not available. |
| */ |
| if (vardata->rel == NULL) |
| return DEFAULT_NUM_DISTINCT; |
| ntuples = vardata->rel->tuples; |
| if (ntuples <= 0.0) |
| return DEFAULT_NUM_DISTINCT; |
| |
| /* |
| * If we had a relative estimate, use that. |
| */ |
| if (stadistinct < 0.0) |
| return floor((-stadistinct * ntuples) + 0.5); |
| |
| /* |
| * With no data, estimate ndistinct = ntuples if the table is small, else |
| * use default. |
| */ |
| if (ntuples < DEFAULT_NUM_DISTINCT) |
| return ntuples; |
| |
| return DEFAULT_NUM_DISTINCT; |
| } |
| |
| /* |
| * get_variable_maximum |
| * Estimate the maximum value of the specified variable. |
| * If successful, store value in *max and return TRUE. |
| * If no data available, return FALSE. |
| * |
| * sortop is the "<" comparison operator to use. (To extract the |
| * minimum instead of the maximum, just pass the ">" operator instead.) |
| */ |
| static bool |
| get_variable_maximum(PlannerInfo *root, VariableStatData *vardata, |
| Oid sortop, Datum *max) |
| { |
| Datum tmax = 0; |
| bool have_max = false; |
| Form_pg_statistic stats; |
| int16 typLen; |
| bool typByVal; |
| Datum *values; |
| int nvalues; |
| int i; |
| HeapTuple tp = getStatsTuple(vardata); |
| |
| if (!HeapTupleIsValid(tp)) |
| { |
| /* no stats available, so default result */ |
| return false; |
| } |
| stats = (Form_pg_statistic) GETSTRUCT(tp); |
| |
| get_typlenbyval(vardata->atttype, &typLen, &typByVal); |
| |
| /* |
| * If there is a histogram, grab the last or first value as appropriate. |
| * |
| * If there is a histogram that is sorted with some other operator than |
| * the one we want, fail --- this suggests that there is data we can't |
| * use. |
| */ |
| if (get_attstatsslot(tp, |
| vardata->atttype, vardata->atttypmod, |
| STATISTIC_KIND_HISTOGRAM, sortop, |
| &values, &nvalues, |
| NULL, NULL)) |
| { |
| if (nvalues > 0) |
| { |
| tmax = datumCopy(values[nvalues - 1], typByVal, typLen); |
| have_max = true; |
| } |
| free_attstatsslot(vardata->atttype, values, nvalues, NULL, 0); |
| } |
| else |
| { |
| Oid rsortop = get_commutator(sortop); |
| |
| if (OidIsValid(rsortop) && |
| get_attstatsslot(tp, |
| vardata->atttype, vardata->atttypmod, |
| STATISTIC_KIND_HISTOGRAM, rsortop, |
| &values, &nvalues, |
| NULL, NULL)) |
| { |
| if (nvalues > 0) |
| { |
| tmax = datumCopy(values[0], typByVal, typLen); |
| have_max = true; |
| } |
| free_attstatsslot(vardata->atttype, values, nvalues, NULL, 0); |
| } |
| else if (get_attstatsslot(tp, |
| vardata->atttype, vardata->atttypmod, |
| STATISTIC_KIND_HISTOGRAM, InvalidOid, |
| &values, &nvalues, |
| NULL, NULL)) |
| { |
| free_attstatsslot(vardata->atttype, values, nvalues, NULL, 0); |
| return false; |
| } |
| } |
| |
| /* |
| * If we have most-common-values info, look for a large MCV. This is |
| * needed even if we also have a histogram, since the histogram excludes |
| * the MCVs. However, usually the MCVs will not be the extreme values, so |
| * avoid unnecessary data copying. |
| */ |
| if (get_attstatsslot(tp, |
| vardata->atttype, vardata->atttypmod, |
| STATISTIC_KIND_MCV, InvalidOid, |
| &values, &nvalues, |
| NULL, NULL)) |
| { |
| bool large_mcv = false; |
| FmgrInfo opproc; |
| |
| fmgr_info(get_opcode(sortop), &opproc); |
| |
| for (i = 0; i < nvalues; i++) |
| { |
| if (!have_max) |
| { |
| tmax = values[i]; |
| large_mcv = have_max = true; |
| } |
| else if (DatumGetBool(FunctionCall2(&opproc, tmax, values[i]))) |
| { |
| tmax = values[i]; |
| large_mcv = true; |
| } |
| } |
| if (large_mcv) |
| tmax = datumCopy(tmax, typByVal, typLen); |
| free_attstatsslot(vardata->atttype, values, nvalues, NULL, 0); |
| } |
| |
| *max = tmax; |
| return have_max; |
| } |
| |
| |
| /*------------------------------------------------------------------------- |
| * |
| * Pattern analysis functions |
| * |
| * These routines support analysis of LIKE and regular-expression patterns |
| * by the planner/optimizer. It's important that they agree with the |
| * regular-expression code in backend/regex/ and the LIKE code in |
| * backend/utils/adt/like.c. Also, the computation of the fixed prefix |
| * must be conservative: if we report a string longer than the true fixed |
| * prefix, the query may produce actually wrong answers, rather than just |
| * getting a bad selectivity estimate! |
| * |
| * Note that the prefix-analysis functions are called from |
| * backend/optimizer/path/indxpath.c as well as from routines in this file. |
| * |
| *------------------------------------------------------------------------- |
| */ |
| |
| /* |
| * Extract the fixed prefix, if any, for a pattern. |
| * |
| * *prefix is set to a palloc'd prefix string (in the form of a Const node), |
| * or to NULL if no fixed prefix exists for the pattern. |
| * *rest is set to a palloc'd Const representing the remainder of the pattern |
| * after the portion describing the fixed prefix. |
| * Each of these has the same type (TEXT or BYTEA) as the given pattern Const. |
| * |
| * The return value distinguishes no fixed prefix, a partial prefix, |
| * or an exact-match-only pattern. |
| */ |
| |
| static Pattern_Prefix_Status |
| like_fixed_prefix(Const *patt_const, bool case_insensitive, |
| Const **prefix_const, Const **rest_const) |
| { |
| char *match; |
| char *patt; |
| int pattlen; |
| char *rest; |
| Oid typeid = patt_const->consttype; |
| int pos, |
| match_pos; |
| bool is_multibyte = (pg_database_encoding_max_length() > 1); |
| |
| /* the right-hand const is type text or bytea */ |
| Assert(typeid == BYTEAOID || typeid == TEXTOID); |
| |
| if (typeid == BYTEAOID && case_insensitive) |
| ereport(ERROR, |
| (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), |
| errmsg("case insensitive matching not supported on type bytea"))); |
| |
| if (typeid != BYTEAOID) |
| { |
| patt = DatumGetCString(DirectFunctionCall1(textout, patt_const->constvalue)); |
| pattlen = strlen(patt); |
| } |
| else |
| { |
| bytea *bstr = DatumGetByteaP(patt_const->constvalue); |
| |
| pattlen = VARSIZE(bstr) - VARHDRSZ; |
| patt = (char *) palloc(pattlen); |
| memcpy(patt, VARDATA(bstr), pattlen); |
| if ((Pointer) bstr != DatumGetPointer(patt_const->constvalue)) |
| pfree(bstr); |
| } |
| |
| match = palloc(pattlen + 1); |
| match_pos = 0; |
| for (pos = 0; pos < pattlen; pos++) |
| { |
| /* % and _ are wildcard characters in LIKE */ |
| if (patt[pos] == '%' || |
| patt[pos] == '_') |
| break; |
| |
| /* Backslash escapes the next character */ |
| if (patt[pos] == '\\') |
| { |
| pos++; |
| if (pos >= pattlen) |
| break; |
| } |
| |
| /* |
| * XXX In multibyte character sets, we can't trust isalpha, so assume |
| * any multibyte char is potentially case-varying. |
| */ |
| if (case_insensitive) |
| { |
| if (is_multibyte && (unsigned char) patt[pos] >= 0x80) |
| break; |
| if (isalpha((unsigned char) patt[pos])) |
| break; |
| } |
| |
| /* |
| * NOTE: this code used to think that %% meant a literal %, but |
| * textlike() itself does not think that, and the SQL92 spec doesn't |
| * say any such thing either. |
| */ |
| match[match_pos++] = patt[pos]; |
| } |
| |
| match[match_pos] = '\0'; |
| rest = &patt[pos]; |
| |
| if (typeid != BYTEAOID) |
| { |
| *prefix_const = string_to_const(match, typeid); |
| *rest_const = string_to_const(rest, typeid); |
| } |
| else |
| { |
| *prefix_const = string_to_bytea_const(match, match_pos); |
| *rest_const = string_to_bytea_const(rest, pattlen - pos); |
| } |
| |
| pfree(patt); |
| pfree(match); |
| |
| /* in LIKE, an empty pattern is an exact match! */ |
| if (pos == pattlen) |
| return Pattern_Prefix_Exact; /* reached end of pattern, so exact */ |
| |
| if (match_pos > 0) |
| return Pattern_Prefix_Partial; |
| |
| return Pattern_Prefix_None; |
| } |
| |
| static Pattern_Prefix_Status |
| regex_fixed_prefix(Const *patt_const, bool case_insensitive, |
| Const **prefix_const, Const **rest_const) |
| { |
| char *match; |
| int pos, |
| match_pos, |
| prev_pos, |
| prev_match_pos; |
| bool have_leading_paren; |
| char *patt; |
| char *rest; |
| Oid typeid = patt_const->consttype; |
| bool is_basic = regex_flavor_is_basic(); |
| bool is_multibyte = (pg_database_encoding_max_length() > 1); |
| |
| /* |
| * Should be unnecessary, there are no bytea regex operators defined. As |
| * such, it should be noted that the rest of this function has *not* been |
| * made safe for binary (possibly NULL containing) strings. |
| */ |
| if (typeid == BYTEAOID) |
| ereport(ERROR, |
| (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), |
| errmsg("regular-expression matching not supported on type bytea"))); |
| |
| /* the right-hand const is type text for all of these */ |
| patt = DatumGetCString(DirectFunctionCall1(textout, patt_const->constvalue)); |
| |
| /* |
| * Check for ARE director prefix. It's worth our trouble to recognize |
| * this because similar_escape() uses it. |
| */ |
| pos = 0; |
| if (strncmp(patt, "***:", 4) == 0) |
| { |
| pos = 4; |
| is_basic = false; |
| } |
| |
| /* Pattern must be anchored left */ |
| if (patt[pos] != '^') |
| { |
| rest = patt; |
| |
| *prefix_const = NULL; |
| *rest_const = string_to_const(rest, typeid); |
| |
| return Pattern_Prefix_None; |
| } |
| pos++; |
| |
| /* |
| * If '|' is present in pattern, then there may be multiple alternatives |
| * for the start of the string. (There are cases where this isn't so, |
| * for instance if the '|' is inside parens, but detecting that reliably |
| * is too hard.) |
| */ |
| if (strchr(patt + pos, '|') != NULL) |
| { |
| rest = patt; |
| |
| *prefix_const = NULL; |
| *rest_const = string_to_const(rest, typeid); |
| |
| return Pattern_Prefix_None; |
| } |
| |
| /* OK, allocate space for pattern */ |
| match = palloc(strlen(patt) + 1); |
| prev_match_pos = match_pos = 0; |
| |
| /* |
| * We special-case the syntax '^(...)$' because psql uses it. But beware: |
| * in BRE mode these parentheses are just ordinary characters. Also, |
| * sequences beginning "(?" are not what they seem, unless they're "(?:". |
| * (We should recognize that, too, because of similar_escape().) |
| * |
| * Note: it's a bit bogus to be depending on the current regex_flavor |
| * setting here, because the setting could change before the pattern is |
| * used. We minimize the risk by trusting the flavor as little as we can, |
| * but perhaps it would be a good idea to get rid of the "basic" setting. |
| */ |
| have_leading_paren = false; |
| if (patt[pos] == '(' && !is_basic && |
| (patt[pos + 1] != '?' || patt[pos + 2] == ':')) |
| { |
| have_leading_paren = true; |
| pos += (patt[pos + 1] != '?' ? 1 : 3); |
| } |
| |
| /* Scan remainder of pattern */ |
| prev_pos = pos; |
| while (patt[pos]) |
| { |
| int len; |
| |
| /* |
| * Check for characters that indicate multiple possible matches here. |
| * Also, drop out at ')' or '$' so the termination test works right. |
| */ |
| if (patt[pos] == '.' || |
| patt[pos] == '(' || |
| patt[pos] == ')' || |
| patt[pos] == '[' || |
| patt[pos] == '^' || |
| patt[pos] == '$') |
| break; |
| |
| /* |
| * XXX In multibyte character sets, we can't trust isalpha, so assume |
| * any multibyte char is potentially case-varying. |
| */ |
| if (case_insensitive) |
| { |
| if (is_multibyte && (unsigned char) patt[pos] >= 0x80) |
| break; |
| if (isalpha((unsigned char) patt[pos])) |
| break; |
| } |
| |
| /* |
| * Check for quantifiers. Except for +, this means the preceding |
| * character is optional, so we must remove it from the prefix too! |
| * Note: in BREs, \{ is a quantifier. |
| */ |
| if (patt[pos] == '*' || |
| patt[pos] == '?' || |
| patt[pos] == '{' || |
| (patt[pos] == '\\' && patt[pos + 1] == '{')) |
| { |
| match_pos = prev_match_pos; |
| pos = prev_pos; |
| break; |
| } |
| if (patt[pos] == '+') |
| { |
| pos = prev_pos; |
| break; |
| } |
| |
| /* |
| * Normally, backslash quotes the next character. But in AREs, |
| * backslash followed by alphanumeric is an escape, not a quoted |
| * character. Must treat it as having multiple possible matches. |
| * In BREs, \( is a parenthesis, so don't trust that either. |
| * Note: since only ASCII alphanumerics are escapes, we don't have |
| * to be paranoid about multibyte here. |
| */ |
| if (patt[pos] == '\\') |
| { |
| if (isalnum((unsigned char) patt[pos + 1]) || patt[pos + 1] == '(') |
| break; |
| pos++; |
| if (patt[pos] == '\0') |
| break; |
| } |
| /* save position in case we need to back up on next loop cycle */ |
| prev_match_pos = match_pos; |
| prev_pos = pos; |
| /* must use encoding-aware processing here */ |
| len = pg_mblen(&patt[pos]); |
| memcpy(&match[match_pos], &patt[pos], len); |
| match_pos += len; |
| pos += len; |
| } |
| |
| match[match_pos] = '\0'; |
| rest = &patt[pos]; |
| |
| if (have_leading_paren && patt[pos] == ')') |
| pos++; |
| |
| if (patt[pos] == '$' && patt[pos + 1] == '\0') |
| { |
| rest = &patt[pos + 1]; |
| |
| *prefix_const = string_to_const(match, typeid); |
| *rest_const = string_to_const(rest, typeid); |
| |
| pfree(patt); |
| pfree(match); |
| |
| return Pattern_Prefix_Exact; /* pattern specifies exact match */ |
| } |
| |
| *prefix_const = string_to_const(match, typeid); |
| *rest_const = string_to_const(rest, typeid); |
| |
| pfree(patt); |
| pfree(match); |
| |
| if (match_pos > 0) |
| return Pattern_Prefix_Partial; |
| |
| return Pattern_Prefix_None; |
| } |
| |
| Pattern_Prefix_Status |
| pattern_fixed_prefix(Const *patt, Pattern_Type ptype, |
| Const **prefix, Const **rest) |
| { |
| Pattern_Prefix_Status result; |
| |
| switch (ptype) |
| { |
| case Pattern_Type_Like: |
| result = like_fixed_prefix(patt, false, prefix, rest); |
| break; |
| case Pattern_Type_Like_IC: |
| result = like_fixed_prefix(patt, true, prefix, rest); |
| break; |
| case Pattern_Type_Regex: |
| result = regex_fixed_prefix(patt, false, prefix, rest); |
| break; |
| case Pattern_Type_Regex_IC: |
| result = regex_fixed_prefix(patt, true, prefix, rest); |
| break; |
| default: |
| elog(ERROR, "unrecognized ptype: %d", (int) ptype); |
| result = Pattern_Prefix_None; /* keep compiler quiet */ |
| break; |
| } |
| return result; |
| } |
| |
| /* |
| * Estimate the selectivity of a fixed prefix for a pattern match. |
| * |
| * A fixed prefix "foo" is estimated as the selectivity of the expression |
| * "variable >= 'foo' AND variable < 'fop'" (see also indxpath.c). |
| * |
| * The selectivity estimate is with respect to the portion of the column |
| * population represented by the histogram --- the caller must fold this |
| * together with info about MCVs and NULLs. |
| * |
| * We use the >= and < operators from the specified btree opclass to do the |
| * estimation. The given variable and Const must be of the associated |
| * datatype. |
| * |
| * XXX Note: we make use of the upper bound to estimate operator selectivity |
| * even if the locale is such that we cannot rely on the upper-bound string. |
| * The selectivity only needs to be approximately right anyway, so it seems |
| * more useful to use the upper-bound code than not. |
| */ |
| static Selectivity |
| prefix_selectivity(VariableStatData *vardata, Oid opclass, Const *prefixcon) |
| { |
| Selectivity prefixsel; |
| Oid cmpopr; |
| FmgrInfo opproc; |
| Const *greaterstrcon; |
| |
| cmpopr = get_opclass_member(opclass, InvalidOid, |
| BTGreaterEqualStrategyNumber); |
| if (cmpopr == InvalidOid) |
| elog(ERROR, "no >= operator for opclass %u", opclass); |
| fmgr_info(get_opcode(cmpopr), &opproc); |
| |
| prefixsel = ineq_histogram_selectivity(vardata, &opproc, true, |
| prefixcon->constvalue, |
| prefixcon->consttype); |
| |
| if (prefixsel <= 0.0) |
| { |
| /* No histogram is present ... return a suitable default estimate */ |
| return 0.005; |
| } |
| |
| /*------- |
| * If we can create a string larger than the prefix, say |
| * "x < greaterstr". |
| *------- |
| */ |
| cmpopr = get_opclass_member(opclass, InvalidOid, |
| BTLessStrategyNumber); |
| if (cmpopr == InvalidOid) |
| elog(ERROR, "no < operator for opclass %u", opclass); |
| fmgr_info(get_opcode(cmpopr), &opproc); |
| |
| greaterstrcon = make_greater_string(prefixcon, &opproc); |
| if (greaterstrcon) |
| { |
| Selectivity topsel; |
| |
| topsel = ineq_histogram_selectivity(vardata, &opproc, false, |
| greaterstrcon->constvalue, |
| greaterstrcon->consttype); |
| |
| /* ineq_histogram_selectivity worked before, it shouldn't fail now */ |
| Assert(topsel > 0.0); |
| |
| /* |
| * Merge the two selectivities in the same way as for a range query |
| * (see clauselist_selectivity()). Note that we don't need to worry |
| * about double-exclusion of nulls, since ineq_histogram_selectivity |
| * doesn't count those anyway. |
| */ |
| prefixsel = topsel + prefixsel - 1.0; |
| |
| /* |
| * A zero or negative prefixsel should be converted into a small |
| * positive value; we probably are dealing with a very tight range and |
| * got a bogus result due to roundoff errors. |
| */ |
| if (prefixsel <= 0.0) |
| prefixsel = 1.0e-10; |
| } |
| |
| return prefixsel; |
| } |
| |
| |
| /* |
| * Estimate the selectivity of a pattern of the specified type. |
| * Note that any fixed prefix of the pattern will have been removed already. |
| * |
| * For now, we use a very simplistic approach: fixed characters reduce the |
| * selectivity a good deal, character ranges reduce it a little, |
| * wildcards (such as % for LIKE or .* for regex) increase it. |
| * |
| * CDB: There is a gradual lessening of the change in selectivity as more |
| * fixed characters or character ranges are added. |
| */ |
| |
| #define FIXED_CHAR_SEL 0.20 /* about 1/5 */ |
| #define CHAR_RANGE_SEL 0.25 |
| #define ANY_CHAR_SEL 0.99 /* not 1, since it won't match end-of-string */ |
| #define CDB_RANCHOR_SEL 0.95 |
| #define CDB_ROLLOFF_SEL 0.14 |
| |
| static Selectivity |
| like_selectivity(Const *patt_const, bool case_insensitive) |
| { |
| Selectivity sel = 1.0; |
| Selectivity fixed_char_sel = FIXED_CHAR_SEL; |
| int pos; |
| Oid typeid = patt_const->consttype; |
| char *patt; |
| int pattlen; |
| |
| /* the right-hand const is type text or bytea */ |
| Assert(typeid == BYTEAOID || typeid == TEXTOID); |
| |
| if (typeid == BYTEAOID && case_insensitive) |
| ereport(ERROR, |
| (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), |
| errmsg("case insensitive matching not supported on type bytea"))); |
| |
| if (typeid != BYTEAOID) |
| { |
| patt = DatumGetCString(DirectFunctionCall1(textout, patt_const->constvalue)); |
| pattlen = strlen(patt); |
| } |
| else |
| { |
| bytea *bstr = DatumGetByteaP(patt_const->constvalue); |
| |
| pattlen = VARSIZE(bstr) - VARHDRSZ; |
| patt = (char *) palloc(pattlen); |
| memcpy(patt, VARDATA(bstr), pattlen); |
| if ((Pointer) bstr != DatumGetPointer(patt_const->constvalue)) |
| pfree(bstr); |
| } |
| |
| /* Skip any leading %; it's already factored into initial sel */ |
| for (pos = 0; pos < pattlen; pos++) |
| { |
| if (patt[pos] != '%' && patt[pos] != '_') |
| break; |
| } |
| |
| for (; pos < pattlen; pos++) |
| { |
| /* % and _ are wildcard characters in LIKE */ |
| if (patt[pos] == '%') |
| {} |
| else if (patt[pos] == '_') |
| sel *= ANY_CHAR_SEL; |
| else |
| { |
| if (patt[pos] == '\\') |
| { |
| /* Backslash quotes the next character */ |
| pos++; |
| if (pos >= pattlen) |
| break; |
| } |
| |
| sel *= fixed_char_sel; |
| fixed_char_sel += (1.0 - fixed_char_sel) * CDB_ROLLOFF_SEL; |
| } |
| } |
| |
| /* CDB: If no trailing wildcard, reduce selectivity slightly. */ |
| if (pos > 0 && |
| patt[pos-1] != '%') |
| sel *= CDB_RANCHOR_SEL; |
| else if (pos >= 2 && |
| patt[pos-2] == '\\') |
| sel *= CDB_RANCHOR_SEL; |
| |
| return sel; |
| } |
| |
| static Selectivity |
| regex_selectivity_sub(char *patt, int pattlen, bool case_insensitive) |
| { |
| Selectivity sel = 1.0; |
| Selectivity fixed_char_sel = FIXED_CHAR_SEL; |
| Selectivity csel; |
| int paren_depth = 0; |
| int paren_pos = 0; /* dummy init to keep compiler quiet */ |
| int pos; |
| |
| for (pos = 0; pos < pattlen; pos++) |
| { |
| if (patt[pos] == '(') |
| { |
| if (paren_depth == 0) |
| paren_pos = pos; /* remember start of parenthesized item */ |
| paren_depth++; |
| } |
| else if (patt[pos] == ')' && paren_depth > 0) |
| { |
| paren_depth--; |
| if (paren_depth == 0) |
| sel *= regex_selectivity_sub(patt + (paren_pos + 1), |
| pos - (paren_pos + 1), |
| case_insensitive); |
| } |
| else if (patt[pos] == '|' && paren_depth == 0) |
| { |
| /* |
| * If unquoted | is present at paren level 0 in pattern, we have |
| * multiple alternatives; sum their probabilities. |
| */ |
| sel += regex_selectivity_sub(patt + (pos + 1), |
| pattlen - (pos + 1), |
| case_insensitive); |
| break; /* rest of pattern is now processed */ |
| } |
| else if (patt[pos] == '[') |
| { |
| bool negclass = false; |
| |
| if (patt[++pos] == '^') |
| { |
| negclass = true; |
| pos++; |
| } |
| if (patt[pos] == ']') /* ']' at start of class is not |
| * special */ |
| pos++; |
| while (pos < pattlen && patt[pos] != ']') |
| pos++; |
| if (paren_depth == 0) |
| { |
| csel = CHAR_RANGE_SEL / FIXED_CHAR_SEL * fixed_char_sel; |
| sel *= (negclass ? (1.0 - csel) : csel); |
| fixed_char_sel += (1.0 - fixed_char_sel) * CDB_ROLLOFF_SEL; |
| } |
| } |
| else if (patt[pos] == '.') |
| { |
| if (paren_depth == 0) |
| sel *= Max(ANY_CHAR_SEL, fixed_char_sel); |
| } |
| else if (patt[pos] == '*' || |
| patt[pos] == '?' || |
| patt[pos] == '+') |
| {} |
| else if (patt[pos] == '{') |
| { |
| while (pos < pattlen && patt[pos] != '}') |
| pos++; |
| } |
| else |
| { |
| /* backslash quotes the next character */ |
| if (patt[pos] == '\\') |
| { |
| pos++; |
| if (pos >= pattlen) |
| break; |
| } |
| if (paren_depth == 0) |
| { |
| sel *= fixed_char_sel; |
| fixed_char_sel += (1.0 - fixed_char_sel) * CDB_ROLLOFF_SEL; |
| } |
| } |
| } |
| if (sel > 1.0) |
| sel = 1.0; |
| return sel; |
| } |
| |
| static Selectivity |
| regex_selectivity(Const *patt_const, bool case_insensitive) |
| { |
| Selectivity sel; |
| char *patt; |
| int pattlen; |
| Oid typeid = patt_const->consttype; |
| |
| /* |
| * Should be unnecessary, there are no bytea regex operators defined. As |
| * such, it should be noted that the rest of this function has *not* been |
| * made safe for binary (possibly NULL containing) strings. |
| */ |
| if (typeid == BYTEAOID) |
| ereport(ERROR, |
| (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), |
| errmsg("regular-expression matching not supported on type bytea"))); |
| |
| /* the right-hand const is type text for all of these */ |
| patt = DatumGetCString(DirectFunctionCall1(textout, patt_const->constvalue)); |
| pattlen = strlen(patt); |
| |
| /* If patt doesn't end with $, consider it to have a trailing wildcard */ |
| if (pattlen > 0 && patt[pattlen - 1] == '$' && |
| (pattlen == 1 || patt[pattlen - 2] != '\\')) |
| { |
| /* has trailing $ */ |
| sel = regex_selectivity_sub(patt, pattlen - 1, case_insensitive); |
| sel *= CDB_RANCHOR_SEL; |
| } |
| else |
| { |
| /* no trailing $ */ |
| sel = regex_selectivity_sub(patt, pattlen, case_insensitive); |
| } |
| return sel; |
| } |
| |
| static Selectivity |
| pattern_selectivity(Const *patt, Pattern_Type ptype) |
| { |
| Selectivity result; |
| |
| switch (ptype) |
| { |
| case Pattern_Type_Like: |
| result = like_selectivity(patt, false); |
| break; |
| case Pattern_Type_Like_IC: |
| result = like_selectivity(patt, true); |
| break; |
| case Pattern_Type_Regex: |
| result = regex_selectivity(patt, false); |
| break; |
| case Pattern_Type_Regex_IC: |
| result = regex_selectivity(patt, true); |
| break; |
| default: |
| elog(ERROR, "unrecognized ptype: %d", (int) ptype); |
| result = 1.0; /* keep compiler quiet */ |
| break; |
| } |
| return result; |
| } |
| |
| |
| /* |
| * Try to generate a string greater than the given string or any |
| * string it is a prefix of. If successful, return a palloc'd string |
| * in the form of a Const node; else return NULL. |
| * |
| * The caller must provide the appropriate "less than" comparison function |
| * for testing the strings. |
| * |
| * The key requirement here is that given a prefix string, say "foo", |
| * we must be able to generate another string "fop" that is greater than |
| * all strings "foobar" starting with "foo". We can test that we have |
| * generated a string greater than the prefix string, but in non-C locales |
| * that is not a bulletproof guarantee that an extension of the string might |
| * not sort after it; an example is that "foo " is less than "foo!", but it |
| * is not clear that a "dictionary" sort ordering will consider "foo!" less |
| * than "foo bar". CAUTION: Therefore, this function should be used only for |
| * estimation purposes when working in a non-C locale. |
| * |
| * To try to catch most cases where an extended string might otherwise sort |
| * before the result value, we determine which of the strings "Z", "z", "y", |
| * and "9" is seen as largest by the locale, and append that to the given |
| * prefix before trying to find a string that compares as larger. |
| * |
| * If we max out the righthand byte, truncate off the last character |
| * and start incrementing the next. For example, if "z" were the last |
| * character in the sort order, then we could produce "foo" as a |
| * string greater than "fonz". |
| * |
| * This could be rather slow in the worst case, but in most cases we |
| * won't have to try more than one or two strings before succeeding. |
| */ |
| Const * |
| make_greater_string(const Const *str_const, FmgrInfo *ltproc) |
| { |
| Oid datatype = str_const->consttype; |
| char *workstr; |
| int len; |
| Datum cmpstr; |
| text *cmptxt = NULL; |
| |
| /* |
| * Get a modifiable copy of the prefix string in C-string format, |
| * and set up the string we will compare to as a Datum. In C locale |
| * this can just be the given prefix string, otherwise we need to add |
| * a suffix. Types NAME and BYTEA sort bytewise so they don't need |
| * a suffix either. |
| */ |
| if (datatype == NAMEOID) |
| { |
| workstr = DatumGetCString(DirectFunctionCall1(nameout, |
| str_const->constvalue)); |
| len = strlen(workstr); |
| cmpstr = str_const->constvalue; |
| } |
| else if (datatype == BYTEAOID) |
| { |
| bytea *bstr = DatumGetByteaP(str_const->constvalue); |
| |
| len = VARSIZE(bstr) - VARHDRSZ; |
| workstr = (char *) palloc(len); |
| memcpy(workstr, VARDATA(bstr), len); |
| if ((Pointer) bstr != DatumGetPointer(str_const->constvalue)) |
| pfree(bstr); |
| cmpstr = str_const->constvalue; |
| } |
| else |
| { |
| workstr = DatumGetCString(DirectFunctionCall1(textout, |
| str_const->constvalue)); |
| len = strlen(workstr); |
| if (lc_collate_is_c() || len == 0) |
| cmpstr = str_const->constvalue; |
| else |
| { |
| /* If first time through, determine the suffix to use */ |
| static char suffixchar = 0; |
| |
| if (!suffixchar) |
| { |
| char *best; |
| |
| best = "Z"; |
| if (varstr_cmp(best, 1, "z", 1) < 0) |
| best = "z"; |
| if (varstr_cmp(best, 1, "y", 1) < 0) |
| best = "y"; |
| if (varstr_cmp(best, 1, "9", 1) < 0) |
| best = "9"; |
| suffixchar = *best; |
| } |
| |
| /* And build the string to compare to */ |
| cmptxt = (text *) palloc(VARHDRSZ + len + 1); |
| SET_VARSIZE(cmptxt, VARHDRSZ + len + 1); |
| memcpy(VARDATA(cmptxt), workstr, len); |
| *(VARDATA(cmptxt) + len) = suffixchar; |
| cmpstr = PointerGetDatum(cmptxt); |
| } |
| } |
| |
| while (len > 0) |
| { |
| unsigned char *lastchar = (unsigned char *) (workstr + len - 1); |
| unsigned char savelastchar = *lastchar; |
| |
| /* |
| * Try to generate a larger string by incrementing the last byte. |
| */ |
| while (*lastchar < (unsigned char) 255) |
| { |
| Const *workstr_const; |
| |
| (*lastchar)++; |
| |
| if (datatype != BYTEAOID) |
| { |
| /* do not generate invalid encoding sequences */ |
| if (!pg_verifymbstr(workstr, len, true)) |
| continue; |
| workstr_const = string_to_const(workstr, datatype); |
| } |
| else |
| workstr_const = string_to_bytea_const(workstr, len); |
| |
| if (DatumGetBool(FunctionCall2(ltproc, |
| cmpstr, |
| workstr_const->constvalue))) |
| { |
| /* Successfully made a string larger than cmpstr */ |
| if (cmptxt) |
| pfree(cmptxt); |
| pfree(workstr); |
| return workstr_const; |
| } |
| |
| /* No good, release unusable value and try again */ |
| pfree(DatumGetPointer(workstr_const->constvalue)); |
| pfree(workstr_const); |
| } |
| |
| /* restore last byte so we don't confuse pg_mbcliplen */ |
| *lastchar = savelastchar; |
| |
| /* |
| * Truncate off the last character, which might be more than 1 byte, |
| * depending on the character encoding. |
| */ |
| if (datatype != BYTEAOID && pg_database_encoding_max_length() > 1) |
| len = pg_mbcliplen(workstr, len, len - 1); |
| else |
| len -= 1; |
| |
| if (datatype != BYTEAOID) |
| workstr[len] = '\0'; |
| } |
| |
| /* Failed... */ |
| if (cmptxt) |
| pfree(cmptxt); |
| pfree(workstr); |
| |
| return NULL; |
| } |
| |
| /* |
| * Generate a Datum of the appropriate type from a C string. |
| * Note that all of the supported types are pass-by-ref, so the |
| * returned value should be pfree'd if no longer needed. |
| */ |
| static Datum |
| string_to_datum(const char *str, Oid datatype) |
| { |
| Assert(str != NULL); |
| |
| /* |
| * We cheat a little by assuming that textin() will do for bpchar and |
| * varchar constants too... |
| */ |
| if (datatype == NAMEOID) |
| return DirectFunctionCall1(namein, CStringGetDatum((char *) str)); |
| else if (datatype == BYTEAOID) |
| return DirectFunctionCall1(byteain, CStringGetDatum((char *) str)); |
| else |
| return DirectFunctionCall1(textin, CStringGetDatum((char *) str)); |
| } |
| |
| /* |
| * Generate a Const node of the appropriate type from a C string. |
| */ |
| static Const * |
| string_to_const(const char *str, Oid datatype) |
| { |
| Datum conval = string_to_datum(str, datatype); |
| |
| return makeConst(datatype, -1, ((datatype == NAMEOID) ? NAMEDATALEN : -1), |
| conval, false, false); |
| } |
| |
| /* |
| * Generate a Const node of bytea type from a binary C string and a length. |
| */ |
| static Const * |
| string_to_bytea_const(const char *str, size_t str_len) |
| { |
| bytea *bstr = palloc(VARHDRSZ + str_len); |
| Datum conval; |
| |
| memcpy(VARDATA(bstr), str, str_len); |
| SET_VARSIZE(bstr, VARHDRSZ + str_len); |
| conval = PointerGetDatum(bstr); |
| |
| return makeConst(BYTEAOID, -1, -1, conval, false, false); |
| } |
| |
| /*------------------------------------------------------------------------- |
| * |
| * Index cost estimation functions |
| * |
| * genericcostestimate is a general-purpose estimator for use when we |
| * don't have any better idea about how to estimate. Index-type-specific |
| * knowledge can be incorporated in the type-specific routines. |
| * |
| * One bit of index-type-specific knowledge we can relatively easily use |
| * in genericcostestimate is the estimate of the number of index tuples |
| * visited. If numIndexTuples is not 0 then it is used as the estimate, |
| * otherwise we compute a generic estimate. |
| * |
| *------------------------------------------------------------------------- |
| */ |
| |
| static void |
| genericcostestimate(PlannerInfo *root, |
| IndexOptInfo *index, List *indexQuals, |
| RelOptInfo *outer_rel, |
| double numIndexTuples, |
| Cost *indexStartupCost, |
| Cost *indexTotalCost, |
| Selectivity *indexSelectivity, |
| double *indexCorrelation) |
| { |
| double numIndexPages; |
| double num_sa_scans; |
| double num_outer_scans; |
| double num_scans; |
| QualCost index_qual_cost; |
| double qual_op_cost; |
| double qual_arg_cost; |
| List *selectivityQuals; |
| ListCell *l; |
| |
| /* |
| * If the index is partial, AND the index predicate with the explicitly |
| * given indexquals to produce a more accurate idea of the index |
| * selectivity. This may produce redundant clauses. We get rid of exact |
| * duplicates in the code below. We expect that most cases of partial |
| * redundancy (such as "x < 4" from the qual and "x < 5" from the |
| * predicate) will be recognized and handled correctly by |
| * clauselist_selectivity(). This assumption is somewhat fragile, since |
| * it depends on predicate_implied_by() and clauselist_selectivity() |
| * having similar capabilities, and there are certainly many cases where |
| * we will end up with a too-low selectivity estimate. This will bias the |
| * system in favor of using partial indexes where possible, which is not |
| * necessarily a bad thing. But it'd be nice to do better someday. |
| * |
| * Note that index->indpred and indexQuals are both in implicit-AND form, |
| * so ANDing them together just takes merging the lists. However, |
| * eliminating duplicates is a bit trickier because indexQuals contains |
| * RestrictInfo nodes and the indpred does not. It is okay to pass a |
| * mixed list to clauselist_selectivity, but we have to work a bit to |
| * generate a list without logical duplicates. (We could just list_union |
| * indpred and strippedQuals, but then we'd not get caching of per-qual |
| * selectivity estimates.) |
| */ |
| if (index->indpred != NIL) |
| { |
| List *strippedQuals; |
| List *predExtraQuals; |
| |
| strippedQuals = get_actual_clauses(indexQuals); |
| predExtraQuals = list_difference(index->indpred, strippedQuals); |
| selectivityQuals = list_concat(predExtraQuals, indexQuals); |
| } |
| else |
| selectivityQuals = indexQuals; |
| |
| /* |
| * Check for ScalarArrayOpExpr index quals, and estimate the number of |
| * index scans that will be performed. |
| */ |
| num_sa_scans = 1; |
| foreach(l, indexQuals) |
| { |
| RestrictInfo *rinfo = (RestrictInfo *) lfirst(l); |
| |
| if (IsA(rinfo->clause, ScalarArrayOpExpr)) |
| { |
| ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) rinfo->clause; |
| int alength = estimate_array_length(lsecond(saop->args)); |
| |
| if (alength > 1) |
| num_sa_scans *= alength; |
| } |
| } |
| |
| /* Estimate the fraction of main-table tuples that will be visited */ |
| *indexSelectivity = clauselist_selectivity(root, selectivityQuals, |
| index->rel->relid, |
| JOIN_INNER, |
| false /* use_damping */); |
| |
| /* |
| * If caller didn't give us an estimate, estimate the number of index |
| * tuples that will be visited. We do it in this rather peculiar-looking |
| * way in order to get the right answer for partial indexes. |
| */ |
| if (numIndexTuples <= 0.0) |
| { |
| numIndexTuples = *indexSelectivity * index->rel->tuples; |
| |
| /* |
| * The above calculation counts all the tuples visited across all |
| * scans induced by ScalarArrayOpExpr nodes. We want to consider the |
| * average per-indexscan number, so adjust. This is a handy place to |
| * round to integer, too. (If caller supplied tuple estimate, it's |
| * responsible for handling these considerations.) |
| */ |
| numIndexTuples = rint(numIndexTuples / num_sa_scans); |
| } |
| |
| /* |
| * We can bound the number of tuples by the index size in any case. Also, |
| * always estimate at least one tuple is touched, even when |
| * indexSelectivity estimate is tiny. |
| */ |
| if (numIndexTuples > index->tuples) |
| numIndexTuples = index->tuples; |
| if (numIndexTuples < 1.0) |
| numIndexTuples = 1.0; |
| |
| /* |
| * Estimate the number of index pages that will be retrieved. |
| * |
| * We use the simplistic method of taking a pro-rata fraction of the total |
| * number of index pages. In effect, this counts only leaf pages and not |
| * any overhead such as index metapage or upper tree levels. In practice |
| * this seems a better approximation than charging for access to the upper |
| * levels, perhaps because those tend to stay in cache under load. |
| */ |
| if (index->pages > 1 && index->tuples > 1) |
| numIndexPages = ceil(numIndexTuples * index->pages / index->tuples); |
| else |
| numIndexPages = 1.0; |
| |
| /* |
| * Now compute the disk access costs. |
| * |
| * The above calculations are all per-index-scan. However, if we are in a |
| * nestloop inner scan, we can expect the scan to be repeated (with |
| * different search keys) for each row of the outer relation. Likewise, |
| * ScalarArrayOpExpr quals result in multiple index scans. This creates |
| * the potential for cache effects to reduce the number of disk page |
| * fetches needed. We want to estimate the average per-scan I/O cost in |
| * the presence of caching. |
| * |
| * We use the Mackert-Lohman formula (see costsize.c for details) to |
| * estimate the total number of page fetches that occur. While this |
| * wasn't what it was designed for, it seems a reasonable model anyway. |
| * Note that we are counting pages not tuples anymore, so we take N = T = |
| * index size, as if there were one "tuple" per page. |
| */ |
| if (outer_rel != NULL && outer_rel->rows > 1) |
| { |
| num_outer_scans = outer_rel->rows; |
| num_scans = num_sa_scans * num_outer_scans; |
| } |
| else |
| { |
| num_outer_scans = 1; |
| num_scans = num_sa_scans; |
| } |
| |
| if (num_scans > 1) |
| { |
| double pages_fetched; |
| |
| /* total page fetches ignoring cache effects */ |
| pages_fetched = numIndexPages * num_scans; |
| |
| /* use Mackert and Lohman formula to adjust for cache effects */ |
| pages_fetched = index_pages_fetched(pages_fetched, |
| index->pages, |
| (double) index->pages, |
| root); |
| |
| /* |
| * Now compute the total disk access cost, and then report a pro-rated |
| * share for each outer scan. (Don't pro-rate for ScalarArrayOpExpr, |
| * since that's internal to the indexscan.) |
| */ |
| *indexTotalCost = (pages_fetched * random_page_cost) / num_outer_scans; |
| } |
| else |
| { |
| /* |
| * For a single index scan, we just charge random_page_cost per page |
| * touched. |
| */ |
| *indexTotalCost = numIndexPages * random_page_cost; |
| } |
| |
| /* |
| * A difficulty with the leaf-pages-only cost approach is that for small |
| * selectivities (eg, single index tuple fetched) all indexes will look |
| * equally attractive because we will estimate exactly 1 leaf page to be |
| * fetched. All else being equal, we should prefer physically smaller |
| * indexes over larger ones. (An index might be smaller because it is |
| * partial or because it contains fewer columns; presumably the other |
| * columns in the larger index aren't useful to the query, or the larger |
| * index would have better selectivity.) |
| * |
| * We can deal with this by adding a very small "fudge factor" that |
| * depends on the index size. The fudge factor used here is one |
| * random_page_cost per 100000 index pages, which should be small enough |
| * to not alter index-vs-seqscan decisions, but will prevent indexes of |
| * different sizes from looking exactly equally attractive. |
| */ |
| *indexTotalCost += index->pages * random_page_cost / 100000.0; |
| |
| /* |
| * CPU cost: any complex expressions in the indexquals will need to be |
| * evaluated once at the start of the scan to reduce them to runtime keys |
| * to pass to the index AM (see nodeIndexscan.c). We model the per-tuple |
| * CPU costs as cpu_index_tuple_cost plus one cpu_operator_cost per |
| * indexqual operator. Because we have numIndexTuples as a per-scan |
| * number, we have to multiply by num_sa_scans to get the correct result |
| * for ScalarArrayOpExpr cases. |
| * |
| * Note: this neglects the possible costs of rechecking lossy operators |
| * and OR-clause expressions. Detecting that that might be needed seems |
| * more expensive than it's worth, though, considering all the other |
| * inaccuracies here ... |
| */ |
| cost_qual_eval(&index_qual_cost, indexQuals, root); |
| qual_op_cost = cpu_operator_cost * list_length(indexQuals); |
| qual_arg_cost = index_qual_cost.startup + |
| index_qual_cost.per_tuple - qual_op_cost; |
| if (qual_arg_cost < 0) /* just in case... */ |
| qual_arg_cost = 0; |
| *indexStartupCost = qual_arg_cost; |
| *indexTotalCost += qual_arg_cost; |
| *indexTotalCost += numIndexTuples * num_sa_scans * (cpu_index_tuple_cost + qual_op_cost); |
| |
| /* |
| * We also add a CPU-cost component to represent the general costs of |
| * starting an indexscan, such as analysis of btree index keys and |
| * initial tree descent. This is estimated at 100x cpu_operator_cost, |
| * which is a bit arbitrary but seems the right order of magnitude. |
| * (As noted above, we don't charge any I/O for touching upper tree |
| * levels, but charging nothing at all has been found too optimistic.) |
| * |
| * Although this is startup cost with respect to any one scan, we add |
| * it to the "total" cost component because it's only very interesting |
| * in the many-ScalarArrayOpExpr-scan case, and there it will be paid |
| * over the life of the scan node. |
| */ |
| *indexTotalCost += num_sa_scans * 100.0 * cpu_operator_cost; |
| |
| /* |
| * Generic assumption about index correlation: there isn't any. |
| */ |
| *indexCorrelation = 0.0; |
| } |
| |
| |
| Datum |
| btcostestimate(PG_FUNCTION_ARGS) |
| { |
| PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); |
| IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(1); |
| List *indexQuals = (List *) PG_GETARG_POINTER(2); |
| RelOptInfo *outer_rel = (RelOptInfo *) PG_GETARG_POINTER(3); |
| Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4); |
| Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5); |
| Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6); |
| double *indexCorrelation = (double *) PG_GETARG_POINTER(7); |
| Oid relid; |
| AttrNumber colnum; |
| HeapTuple tuple; |
| double numIndexTuples; |
| List *indexBoundQuals; |
| int indexcol; |
| bool eqQualHere; |
| bool found_saop; |
| double num_sa_scans; |
| ListCell *l; |
| cqContext *stacqCtx; |
| |
| /* |
| * CDB: Tell caller how many leading indexcols are matched by '=' quals. |
| * |
| * CDB TODO: The num_leading_eq field doesn't really belong in IndexOptInfo. |
| * It's just a kludgy way to return an extra result parameter, because we |
| * don't have access here to the IndexPath node where this info should go. |
| */ |
| index->num_leading_eq = 0; |
| |
| /* |
| * For a btree scan, only leading '=' quals plus inequality quals for the |
| * immediately next attribute contribute to index selectivity (these are |
| * the "boundary quals" that determine the starting and stopping points of |
| * the index scan). Additional quals can suppress visits to the heap, so |
| * it's OK to count them in indexSelectivity, but they should not count |
| * for estimating numIndexTuples. So we must examine the given indexQuals |
| * to find out which ones count as boundary quals. We rely on the |
| * knowledge that they are given in index column order. |
| * |
| * For a RowCompareExpr, we consider only the first column, just as |
| * rowcomparesel() does. |
| * |
| * If there's a ScalarArrayOpExpr in the quals, we'll actually perform N |
| * index scans not one, but the ScalarArrayOpExpr's operator can be |
| * considered to act the same as it normally does. |
| */ |
| indexBoundQuals = NIL; |
| indexcol = 0; |
| eqQualHere = false; |
| found_saop = false; |
| num_sa_scans = 1; |
| foreach(l, indexQuals) |
| { |
| RestrictInfo *rinfo = (RestrictInfo *) lfirst(l); |
| Expr *clause; |
| Node *leftop, |
| *rightop; |
| Oid clause_op; |
| int op_strategy; |
| |
| Assert(IsA(rinfo, RestrictInfo)); |
| clause = rinfo->clause; |
| if (IsA(clause, OpExpr)) |
| { |
| leftop = get_leftop(clause); |
| rightop = get_rightop(clause); |
| clause_op = ((OpExpr *) clause)->opno; |
| } |
| else if (IsA(clause, RowCompareExpr)) |
| { |
| RowCompareExpr *rc = (RowCompareExpr *) clause; |
| |
| leftop = (Node *) linitial(rc->largs); |
| rightop = (Node *) linitial(rc->rargs); |
| clause_op = linitial_oid(rc->opnos); |
| } |
| else if (IsA(clause, ScalarArrayOpExpr)) |
| { |
| ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) clause; |
| |
| leftop = (Node *) linitial(saop->args); |
| rightop = (Node *) lsecond(saop->args); |
| clause_op = saop->opno; |
| found_saop = true; |
| } |
| else |
| { |
| elog(ERROR, "unsupported indexqual type: %d", |
| (int) nodeTag(clause)); |
| continue; /* keep compiler quiet */ |
| } |
| if (match_index_to_operand(leftop, indexcol, index)) |
| { |
| /* clause_op is correct */ |
| } |
| else if (match_index_to_operand(rightop, indexcol, index)) |
| { |
| /* Must flip operator to get the opclass member */ |
| clause_op = get_commutator(clause_op); |
| } |
| else |
| { |
| /* Must be past the end of quals for indexcol, try next */ |
| if (!eqQualHere) |
| break; /* done if no '=' qual for indexcol */ |
| indexcol++; |
| eqQualHere = false; |
| if (match_index_to_operand(leftop, indexcol, index)) |
| { |
| /* clause_op is correct */ |
| } |
| else if (match_index_to_operand(rightop, indexcol, index)) |
| { |
| /* Must flip operator to get the opclass member */ |
| clause_op = get_commutator(clause_op); |
| } |
| else |
| { |
| /* No quals for new indexcol, so we are done */ |
| break; |
| } |
| } |
| op_strategy = get_op_opclass_strategy(clause_op, |
| index->classlist[indexcol]); |
| Assert(op_strategy != 0); /* not a member of opclass?? */ |
| if (op_strategy == BTEqualStrategyNumber) |
| { |
| eqQualHere = true; |
| |
| /* CDB: Count leading indexcols having '=' quals. */ |
| if (!IsA(clause, ScalarArrayOpExpr)) |
| index->num_leading_eq = indexcol + 1; |
| } |
| |
| /* count up number of SA scans induced by indexBoundQuals only */ |
| if (IsA(clause, ScalarArrayOpExpr)) |
| { |
| ScalarArrayOpExpr *saop = (ScalarArrayOpExpr *) clause; |
| int alength = estimate_array_length(lsecond(saop->args)); |
| |
| if (alength > 1) |
| num_sa_scans *= alength; |
| } |
| indexBoundQuals = lappend(indexBoundQuals, rinfo); |
| } |
| |
| /* |
| * If index is unique and we found an '=' clause for each column, we can |
| * just assume numIndexTuples = 1 and skip the expensive |
| * clauselist_selectivity calculations. |
| */ |
| if (index->unique && |
| index->num_leading_eq == index->ncolumns) |
| numIndexTuples = 1.0; |
| else |
| { |
| Selectivity btreeSelectivity; |
| |
| btreeSelectivity = clauselist_selectivity(root, indexBoundQuals, |
| index->rel->relid, |
| JOIN_INNER, |
| false /* use_damping */); |
| numIndexTuples = btreeSelectivity * index->rel->tuples; |
| /* |
| * As in genericcostestimate(), we have to adjust for any |
| * ScalarArrayOpExpr quals included in indexBoundQuals, and then |
| * round to integer. |
| */ |
| numIndexTuples = rint(numIndexTuples / num_sa_scans); |
| } |
| |
| genericcostestimate(root, index, indexQuals, outer_rel, numIndexTuples, |
| indexStartupCost, indexTotalCost, |
| indexSelectivity, indexCorrelation); |
| |
| /* |
| * If we can get an estimate of the first column's ordering correlation C |
| * from pg_statistic, estimate the index correlation as C for a |
| * single-column index, or C * 0.75 for multiple columns. (The idea here |
| * is that multiple columns dilute the importance of the first column's |
| * ordering, but don't negate it entirely. Before 8.0 we divided the |
| * correlation by the number of columns, but that seems too strong.) |
| * |
| * We can skip all this if we found a ScalarArrayOpExpr, because then the |
| * call must be for a bitmap index scan, and the caller isn't going to |
| * care what the index correlation is. |
| */ |
| if (found_saop) |
| PG_RETURN_VOID(); |
| |
| if (index->indexkeys[0] != 0) |
| { |
| /* Simple variable --- look to stats for the underlying table */ |
| relid = getrelid(index->rel->relid, root->parse->rtable); |
| Assert(relid != InvalidOid); |
| colnum = index->indexkeys[0]; |
| } |
| else |
| { |
| /* Expression --- maybe there are stats for the index itself */ |
| relid = index->indexoid; |
| colnum = 1; |
| } |
| |
| stacqCtx = caql_beginscan( |
| NULL, |
| cql("SELECT * FROM pg_statistic " |
| " WHERE starelid = :1 " |
| " AND staattnum = :2 ", |
| ObjectIdGetDatum(relid), |
| Int16GetDatum(colnum))); |
| |
| tuple = caql_getnext(stacqCtx); |
| |
| if (HeapTupleIsValid(tuple)) |
| { |
| float4 *numbers; |
| int nnumbers; |
| |
| if (get_attstatsslot(tuple, InvalidOid, 0, |
| STATISTIC_KIND_CORRELATION, |
| index->ordering[0], |
| NULL, NULL, &numbers, &nnumbers)) |
| { |
| double varCorrelation; |
| |
| Assert(nnumbers == 1); |
| varCorrelation = numbers[0]; |
| |
| if (index->ncolumns > 1) |
| *indexCorrelation = varCorrelation * 0.75; |
| else |
| *indexCorrelation = varCorrelation; |
| |
| free_attstatsslot(InvalidOid, NULL, 0, numbers, nnumbers); |
| } |
| } |
| caql_endscan(stacqCtx); |
| |
| PG_RETURN_VOID(); |
| } |
| |
| Datum |
| hashcostestimate(PG_FUNCTION_ARGS) |
| { |
| PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); |
| IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(1); |
| List *indexQuals = (List *) PG_GETARG_POINTER(2); |
| RelOptInfo *outer_rel = (RelOptInfo *) PG_GETARG_POINTER(3); |
| Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4); |
| Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5); |
| Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6); |
| double *indexCorrelation = (double *) PG_GETARG_POINTER(7); |
| |
| genericcostestimate(root, index, indexQuals, outer_rel, 0.0, |
| indexStartupCost, indexTotalCost, |
| indexSelectivity, indexCorrelation); |
| |
| PG_RETURN_VOID(); |
| } |
| |
| Datum |
| gistcostestimate(PG_FUNCTION_ARGS) |
| { |
| PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); |
| IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(1); |
| List *indexQuals = (List *) PG_GETARG_POINTER(2); |
| RelOptInfo *outer_rel = (RelOptInfo *) PG_GETARG_POINTER(3); |
| Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4); |
| Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5); |
| Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6); |
| double *indexCorrelation = (double *) PG_GETARG_POINTER(7); |
| |
| genericcostestimate(root, index, indexQuals, outer_rel, 0.0, |
| indexStartupCost, indexTotalCost, |
| indexSelectivity, indexCorrelation); |
| |
| PG_RETURN_VOID(); |
| } |
| |
| Datum |
| gincostestimate(PG_FUNCTION_ARGS) |
| { |
| PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); |
| IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(1); |
| List *indexQuals = (List *) PG_GETARG_POINTER(2); |
| RelOptInfo *outer_rel = (RelOptInfo *) PG_GETARG_POINTER(3); |
| Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4); |
| Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5); |
| Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6); |
| double *indexCorrelation = (double *) PG_GETARG_POINTER(7); |
| |
| genericcostestimate(root, index, indexQuals, outer_rel, 0.0, |
| indexStartupCost, indexTotalCost, |
| indexSelectivity, indexCorrelation); |
| |
| PG_RETURN_VOID(); |
| } |
| |
| Datum |
| bmcostestimate(PG_FUNCTION_ARGS) |
| { |
| PlannerInfo *root = (PlannerInfo *) PG_GETARG_POINTER(0); |
| IndexOptInfo *index = (IndexOptInfo *) PG_GETARG_POINTER(1); |
| List *indexQuals = (List *) PG_GETARG_POINTER(2); |
| RelOptInfo *outer_rel = (RelOptInfo *) PG_GETARG_POINTER(3); |
| Cost *indexStartupCost = (Cost *) PG_GETARG_POINTER(4); |
| Cost *indexTotalCost = (Cost *) PG_GETARG_POINTER(5); |
| Selectivity *indexSelectivity = (Selectivity *) PG_GETARG_POINTER(6); |
| double *indexCorrelation = (double *) PG_GETARG_POINTER(7); |
| |
| List *selectivityQuals; |
| double numIndexTuples; |
| List *groupExprs = NIL; |
| int i; |
| double numDistinctValues; |
| |
| /* |
| * Estimate the number of index tuples. This is basically the same |
| * as the one in genericcostestimate(), except that |
| * (1) We don't consider ScalarArrayOpExpr in the calculation, since |
| * each value has its own bit vector. |
| * (2) since the bitmap index stores bit vectors, one for each distinct |
| * value, we adjust the number of index tuples by dividing the |
| * value with the number of distinct values. |
| */ |
| if (index->indpred != NIL) |
| { |
| List *strippedQuals; |
| List *predExtraQuals; |
| |
| strippedQuals = get_actual_clauses(indexQuals); |
| predExtraQuals = list_difference(index->indpred, strippedQuals); |
| selectivityQuals = list_concat(predExtraQuals, indexQuals); |
| } |
| else |
| selectivityQuals = indexQuals; |
| |
| /* Estimate the fraction of main-table tuples that will be visited */ |
| *indexSelectivity = clauselist_selectivity(root, selectivityQuals, |
| index->rel->relid, |
| JOIN_INNER, |
| false /* use_damping */); |
| |
| /* |
| * Construct a list of index keys, so that we can estimate the number |
| * of distinct values for those keys. |
| */ |
| for (i = 0; i < index->ncolumns; i ++) |
| { |
| if (index->indexkeys[i] > 0) |
| { |
| Var *var = find_indexkey_var(root, index->rel, (AttrNumber) index->indexkeys[i]); |
| |
| groupExprs = lappend(groupExprs, var); |
| } |
| } |
| if (index->indexprs != NULL) |
| groupExprs = list_concat_unique(groupExprs, index->indexprs); |
| |
| Assert(groupExprs != NULL); |
| numDistinctValues = estimate_num_groups(root, groupExprs, index->rel->rows); |
| if (numDistinctValues == 0) |
| numDistinctValues = 1; |
| |
| numIndexTuples = *indexSelectivity * index->rel->tuples; |
| numIndexTuples = rint(numIndexTuples / numDistinctValues); |
| |
| genericcostestimate(root, index, indexQuals, outer_rel, numIndexTuples, |
| indexStartupCost, indexTotalCost, |
| indexSelectivity, indexCorrelation); |
| |
| PG_RETURN_VOID(); |
| } |